Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...

icmm.csic.es

Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...

Wüest M. 51

Wykes M. 82

Yamaguchi M. 17

Ybarra G. 129

Yubero F. 20, 23

Yurasova V.E. 15

Zelaya-Angel O. 17, 127, 128

Zykova E.Yu. 15

149


Rusu G.I. 131

Rusu M. 126, 131

Ryzhov Yu.A. 15

Sacedón J.L. 25, 72

Sánchez O. 100, 103

Sánchez-López J.C. 101

Sanguino P. 116

Schwarz R. 116

Shakarban I.I. 15

Silva R.F. 9, 99-140

Simao R.A. 99

Smail H. 46

Solis J. 78

Soriano L. 10

Stupnik A. 88

Tabarés F.L. 30, 33

Tafalla D. 33

Tavares C.J. 21, 117

Teba, D. 61

Teixeira M.R. 90

Teixeira V. 21, 117

Teodoro O.M.N.D. 48, 70, 89, 91, 116, 120

Tesar J. 69

Tessema G. 122

Tikhomirov A.V. 31

Tilford Ch. R. 6

Torres-Kauffman J. 128

Trigo J.F. 10, 61

Valencia-Alvarado R. 124

Vanhulsel A. 94

Vaz F. 75, 98

Vázquez E. 121

Vázquez L. 37

Verheyde B. 94

Verhoeven J. 56

Vicar M. 69

Vidal-Larramendi J. 127

Vieira P. 93

Vigil-Galán O. 127

Vila M. 24,138

Vilajuana T. 64

Villuendas F. 60

Völklein F. 106

Wemans A. 42,45,48

Wilhelm M. 116

148


Oliveira F. J. 140

Orts M.J. 76

Otal P. 71

Ouchabane M. 125

Paiva A.C.S. 95

Palacín S. 10

Palomino-Merino R. 128

Pardo A. 113

Parreira N.M.G. 16, 102

Patscheider J. 14

Pearce R.J.H. 82

Peksa L. 69

Peña-Eguiluz R. 124

Pereira P.J.S. 90

Pérez-Martín A.M.C. 22

Piechowiak M. 44

Pinto R.M. 92

Polcar T. 16, 96

Portillo-Moreno O. 17, 128

Powell S. 58

Prazak D. 69

Preda I. 10

Prepelita P. 131

Prieto C. 26, 138

Raboso D. 130

Ramos A.R. 21

Ramos-Barrado J.R. 47

Rayon E. 11

Rebouta L. 98

Reid R.J. 50

Reis E.M.C.C. 89

Repa P. 69

Ribera J. 77

Rico M. 104

Rico V. 23

Rico J. 20

Rios P. 113

Rodríguez R.J. 36, 38, 104, 112

Rodríguez-Cañas E. 25

Román E. 94, 109, 130

Romero J. 13

Rueda F. 121

Ruiz A. 130

Ruiz S. 53

Rusu G.G. 126

147


Leinen D. 47

Leisch M. 88

Lévy L. 113

López-Callejas R. 124

López-Cartes C. 101

López-Ibáñez R. 47

Lousa A. 13, 41

Lozada-Morales R. 17, 128

Lozano P. 130

Lucas F. 76

Maneira M.J.P. 42, 45, 48, 90

Marco J.M. 59

Mardare D. 119

Mari D. 67

Marín M. 100

Marques H.P. 48, 70, 91

Marques S.M. 21, 117

Martín F. 47

Martínez L. 94

Martínez R. 36, 38, 104

Martínez-Martínez D. 101

Matilla C. 32, 53

Matveeva E. 11, 63

Medina N. 53

Meier A. 106

Mejia J.P. 41

Mendez J. 94

Mercado-Cabrera A. 124

Miralles LL. 107

Mohammedi L. 137

Moina C. 129

Montero I. 112, 113, 130

Mosunov A.S. 15

Moutinho A.M.C. 70, 91, 120

Moya J.S. 72

Muñoz-Castro A.E. 124

Narayanan K.L. 17

Neto M.A. 9

Nevshupa, R. 109

Nunes Y. 42, 45, 48

Nunzi J.M. 118

Ochando I.M. 26, 138

Orgaz F. 79

Oliva A.I. 25

Oliveira F. 24

146


Gabouze N. 125

Galán L. 112, 113, 130

García G. 36

García J.A. 36, 38, 79, 104

García M. 130

García-López F.J. 26

García-Luis A. 12, 129, 136

García-Rocha M. 128

Garg D. 20

Gheriani R. 133, 137

Gikal B.N. 31

Girtan M. 118, 126

Godoy-Cabrera O.G. 124

Gomes J.R. 99

Gomes M.J.M. 44

Gómez-Aleixandre C. 37

González D. 12, 129, 136

González R. 114

González-Elipe A.R. 20, 23, 43, 62

Gordo P.R. 42, 45

Gracia F. 62

Gronych T. 69

Guerra M. 95

Gulbekian G.G. 31

Gutierrez A. 10

Gutiérrez M.T. 27

Hadjar Y. 135-139

Halimi R. 133, 134, 135, 137-139

Harkati C. 134

Herrasti P. 121

Hidalgo J.M. 52, 68

Högberg H. 86

Huttel Y. 94

Jacobs R. 94

Jensen H.S. 108

Jiménez-Rioboó R.J. 26

Jiménez-Rodríguez J.J. 22

Jiménez-Sáez J.C. 22

Jousten K. 29

Khalfallah F, 139

Khodorov A. 44

Kreissing U. 98

Kunst M. 116

Lara A. 61

Legras J-C. 71

145


Cavaleiro A. 16, 39, 79, 96, 102

Chigiatto P. 81

Coelho B. 24

Colera I. 114

Colligon J.S. 15

Contreras-Puente G. 127

Corengia P. 136, 129

Costa F.M. 9

Costa M.L. 89, 92, 93

Cotrino J. 20, 43

Cristo P.M.S. 93

Dabos-Seignon S. 118

Daniel B. 58

Day Ch. 108

de la Piedad-Beneitez A. 124

de la Rosa-Vázquez J. 124

de las Heras E. 129

de Segovia J.L. 52, 68, 109, 112, 113, 114

Devia A. 41

Dias A.A. 89,92, 93

Díaz B. 100

Díaz M. 72

Díaz R. 121

Duarte A. 24

Dumitru L. 119

Van Eesbeek M. 113

Elovikov S.S. 15

Escobar Galindo R. 11, 26

Escrivao M.L. 90

Espinós J.P. 20, 23

Esteve J. 41

Evaristo M. 96

Falcony C. 103

Fazio G. 83

Ferreira Q. 48

Fernandes A.J. 21, 117

Fernandes A.J.S. 9, 24-140

Fernández A. 101

Ferrerira J.A. 30, 33

Ferreira R. 19

Fonseca A.P. 70

Freitas P.P. 19

Freitas S. 19

Frutos F. 23

Fuentes G.G. 38, 112

144


AUTHOR’S INDEX

Aouabdia Y. 46

Ababou A. 125

Abb el Lefdil M. 121

Abdel Hamid B. 46

Achete C.A. 99

Acuña R. 61

Afonso C.N. 65

Agote I. 136

Aguilar-Hernández J. 127

Aissani L. 134

Ait-Hamouda K. 125

Al-Dmour E. 107

Albella J.M. 11, 37, 79,103

Alberdi A. 76, 100

Almeida F. A. 140

Álvarez L. 94

Alves E. 21, 98

Amaral M. S. 140

Andrés M. 27

Araiza J.J. 103

Arias-Carbajal A. 127

Auger M.A. 103

Aznárez J.A. 25

Baban C. 131

Barocio S.R. 124

Barradas N.P. 98

Barranco A. 43, 62

Belda A. 76

Bellido-González V. 58

Bergoglio M. 67

Boineau F. 71

Borrás A. 43, 62

Brizuela M. 12, 129, 136

Buijnsters J.G. 37

Cáceres D. 26, 114

Calcatelli A. 67

Camargao S.S. 99

Camero M. 37

Canário A.R. 91, 120

Carda J. 77

Carneiro J.O. 21, 117

Carrapichano J.M. 99

Carvalho P. 75

143


142


AUTHORS’S INDEX

141


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P.8 NANO TO MICROMETRIC HFCVD DIAMOND ADHESION STRENGTH

TO Si 3 N 4 . F.A. Almeida, M.S. Amaral, F.J. Oliveira, R.F. Silva. Dept. of Ceramics and Glass Engineering,

CICECO, Univ. of Aveiro, 3810-193 Aveiro, Portugal. A.J.S. Fernandes. Dept. of Physics,

Univ. of Aveiro, 3810-193 Aveiro, Portugal

CVD diamond coated materials possess unique properties (hardness, thermal conductivity, chemical

inertness) that demand their selection as components of tribosystems working under mechanical

and/or chemical severe conditions. Examples of such applications are cutting tools for highly abrasive

materials and mechanical seals for pumping of corrosive liquids. Furthermore, an increasing interesting

field of application is biomedicine, namely cirurgical tools and coatings for articular implants,

where diamond’s biocompatibility is an essential issue. However, the high surface roughness of conventional

microcrystalline CVD diamond is a major problem when considering such purposes, as the

sliding contact of diamond asperities may increase stress and temperature levels, leading to an increasing

wear rate. To overcome this drawback, today’s goal is the development of diamond crystals with

very small grains of nanometric size by adequate CVD parameters, avoiding the typical columnar

growth of microcrystalline diamond structures. When considering tribological and mechanical applications,

adhesion of the film to the substrate determines the success of the component in service. In this

study, distinct diamond coatings on silicon nitride ceramic substrates with different crystallite sizes

were investigated: i) nanocrystalline diamond (~25 nm); ii) submicrometric diamond (~ 40 nm); and

iii) conventional micrometric size (~10 μm). The coatings, with thickness of about 40 μm, were grown

by hot filament CVD technique. The effect of these diamond structures on adhesion strength to the ceramic

substrate will be evaluated by Brale tip indentation and correlated with their Raman signature.

140


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P.7 STUDY OF SOME PROPERTIES OF HARD TUNGSTEN CARBIDE

COATINGS. F. Khalfallah, Y. Hadjar, R. Halimi. Laboratoire des Couches Minces et Interfaces,

Département de Physique, Faculté des Sciences, Université Mentouri, 25000 Constantine, Algérie.

In this work, we have studied the properties of hard coatings of tungsten carbides. The samples are

thin layers of Tungsten deposited at 500°C on two types of steel (containing 1 and 0,7% wt. carbon)

substrates. The samples were then heat treated in vacuum, at various temperatures (500-1000°C) and

during different times.

The formation of tungsten carbides, the evolution of the microstructure and the morphology of the surface

of samples were followed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

The measurements of micro-hardness were carried out by Vickers tests.

Thermal annealing produces reactions and some other structural changes in the tungsten layers which

depend on the carbon content in substrate.

It is established that the formation of tungsten carbides occurs above annealing at 800°C. The reaction

is more rapid on substrate containing 1%C. The mono-carbide WC forms after annealing at 1000°C.

The hardness of coatings increases continuously from 400 to 1200 Kg/mm² as the temperature of annealing

increases from 500 to 900°C. The samples rich on carbon show higher hardness.

Key words: hard coatings, tungsten, carbides, thin films.

Presenting author: F. KHALFALLAH

Contacts and email: Tel/Fax: 213 31 61 47 11; fa_fares@yahoo.fr

Presentation type: Poster

139


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P.6 OPTICAL AND STRUCTURAL STUDY OF EB-PVD ZrO 2 THIN FILMS.I.

M. Ochando, M. Vila and C. Prieto. Instituto de Ciencia de Materiales de Madrid, Consejo Superior

de Investigaciones Científicas. Cantoblanco, 28049 – MADRID, Spain.

Zirconium oxide is a widely used material because of its heat resistance, low thermal conductivity,

high refractive index and high transparency in the visible and near infrared region, very high chemical

inertness and high laser damage threshold. Due to these properties, its applications can be found in

very different aspects of technology. For instance, zirconia has been applied as thermal barrier coating

(1), optical filters, laser mirrors(2), buffer layer for high T C superconductor on Si (3), high temperature

oxygen separation (4), oxygen sensors(5), and solid oxide fuel cells(6).

Films of zirconia can be prepared by different techniques. Typically, thin films prepared by sputtering

are used for gate dielectric in microelectronics applications and zirconia films prepared by electron

beam physical vapour deposition (EB-PVD) are candidates for advanced thermal barrier coatings

(TBC) for the new generation of land-based gas turbines as well as for optical applications. In the interest

host materials with a high luminescent efficiency and superior stabilization, tetragonal ZrO2 is

an attractive material due to the refractive index, electrical, chemical and mechanical characteristics.

ZrO 2 thin films prepared on Si(100) substrates by electron beam physical vapour deposition (EB-

PVD) are investigated by X-ray diffraction and optical absorption spectroscopy. Results show tetragonal

stabilized phases of zirconium oxide independently of the yttria addition in the starting material. In

this work, it is reported the variation of the crystallite size as a function of the deposition rate, showing

that crystallites are in the nanometric range and that a remarkable crystallite size increase is observable

for thin films prepared at low deposition rates.

In addition, it is presented the optical absorption spectroscopy characterization in order to determine

the refractive index; the obtained values does not depend on the deposition rate being in agreement

with the bulk ones. It is shown EB-PVD prepared samples have good performance for optical and protective

coatings.

2

3

4

5

6

S.M. Meier, D.K. Gupta, J Eng. Gas Turbines Power Trans. ASME 116 (1994) 250.

W.H. Lowdermilk, D. Milam, F. Rainer, Thin Solid Films 73 (1980) 155.

D.K. Fork, D.B. Fenner, G.A.N. Connell, J.M. Phillips, T.H. Geballe, Appl. Phys. Lett. 57 (1990) 1137.

J. Han, Y.Zeng, G. Xomeritakis, Y.S. Lin, Solid State Ionics 98 (1997) 63.

M. Sayer , K.Sreenivas, Science 247 (1990) 1056.

N.Q. Minh, J. Am. Ceram. Soc. 76 (1993) 563.

138


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P.5 ELABORATION AND CHARACTERIZATION OF THIN TITANIUM

COATINGS ON HIGH CARBON STEEL SUBSTRATES. L. Mohammedi. Laboratory of Materials

Physic. University of Ouargla – 30 000 – Algeria. R. Gheriani. Laboratory of Materials Physic.

University of Ouargla – 30 000 – Algeria. R. Halimi. Laboratoire Couches Minces et Interfaces, Campus

Chaâb Erssas, Université Mentouri de Constantine - 25 000 Constantine – Algérie.

In this work we have elaborated, by cathodic sputtering, thin titanium coatings on steel substrates containing

≈ 2% Wt of carbon. The so prepared samples are submitted to various thermal anneals in vacuum

between 400°C and 1000°C, and then characterized structurally and mechanically by X-ray diffraction

(XRD), scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and hardness

tests. The analysis of samples showed the formation and the growth of titanium carbide above

400°C. It is established that carbon, iron and titanium atoms interdiffuse intensively, and form a diffusion

zone which is, roughly, homogeneous and essentially constituted from titanium carbide. This new

layer presents a good performances (for example, at 900°C, the value of microhardness is H v = 3200

kg mm -2 , which is larger than that of bulk TiC H v = 3000 kg mm -2 ).

Key words: thin films, hard coatings, carbide, diffusion, titanium

137


JUNE 28 WEDNESDAY AFTERNOON

ETCHC-WeA-P.4 DEPOSITION OF Ti-B-Al-N COATINGS BY MAGNETRON SPUT-

TERING OF COMPOSITE SHS TARGETS. A. García-Luis * , M. Brizuela, P. Corengia, D. González,

I. Agote. INASMET-Tecnalia, Paseo de Mikeletegi 2, 20009 San Sebastián, Spain

The synthesis of complex multicomponent coatings by magnetron sputtering usually involves the use

of several single-material targets, multi-material targets or composite targets. There are several methods

of producing composite targets, for example, hot pressing, hot extrusion, hot isostatic pressing or

plasma spraying of the component materials of the target. However, each of these methods has some

limitations regarding purity, porosity, uniformity of the microstructure or manufacturing costs. Self-

Propagating High-temperature Synthesis (SHS) is an energy-efficient alternative method which uses

exothermic reactions to synthesize compact and pure inorganic materials, including intermetallics, ceramics

and ceramic composites.

In this work, Ti/TiB 2 (5 % Al) composite targets produced by the SHS technique has been used to deposit

PVD coatings based in Ti-B-Al-N compositions. The process optimization has included the

study of the experimental parameters (cathode power, gas flows and heating on the chamber) on the

coating properties. Mechanical properties have been evaluated by dynamic ultramicroindentation

techniques and scratch testing, while tribological tests have been carried out against ball bearing steel

by the pin-on-disk method.

Ultramicrohardness values up to 36 GPa, together with a very good elastic behaviour (elastic work 92

%) have been obtained for some selected Ti-B-Al-N coatings. The adhesion of these coatings to steel

substrates has been satisfactory, with values of critical load in the scratch test higher than 55 N. Finally,

the wear tests confirm the good tribological properties of these coatings, giving no measurable

wear of the coated disk after the pin-on-disk test.

* Corresponding author: Tel: +34 943 003700; fax: +34 943 003800, e-mail: agarcia@inasmet.es

136


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P3 CARBIDES FORMATION IN TANTALUM THIN LAYERS DEPOS-

ITED ON STEEL SUBSTRATES. Y. Hadjar. Institut de Tronc Commun Sciences Exactes et

Technologie, Université de Batna, Algérie, R. Halimi, Laboratoire Couches Minces et Interfaces,

Université Mentouri, 25000 Constantine, Algérie.

In the present work we are intending to elaborate and to study thin film coating of tantalum carbides

on steel substrates. The procedure used in order to prepare the samples consist on depositing, by

electron gun evaporation, a thin film (4µm thickness) of tantalum on steel substrates containing 1

%wt. of carbon, then, annealing the system (substrate/coating) in vacuum at a temperature at which

the carbon of the substrate may diffuse into the Ta metallic film. This fact leads to the formation of

tantalum carbides. The effects of the annealing on the kinetic of tantalum carbides formation and

morphology have been investigated using X- ray diffraction (XRD), secondary ion mass spectroscopy

(SIMS) and scanning electron microscopy (SEM). The mechanical characterization was performed

by measuring microhardness and adhesion. It is found that at annealing up to 800°C the

compounds Ta 2 C and TaC are formed. During the subsequent heat treatment from 900°C to 1100°C

the final TaC phase grows at the expense of the Ta2C phase. Moreover, the microhardness and adhesion

of the films increase significantly with increasing annealing temperature. At a given temperature,

the microhardness increases, with the rise of the annealing time, to reach a maximum and then

decreases. The final coating layer has a golden color and presents a columnar structure. The formation

mechanisms are discussed.

Key words: hard coatings, tantalum carbides, thin films, diffusion.

Presenting author: R. HALIMI

E-mail: rachid_halimi@yahoo.fr

Presentation type: Poster

135


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P.2 SYNTHESIS AND CHARACTERIZATION OF THIN HARD COAT-

INGS OF CHROMIUM CARBIDES. L. Aissani. Département de Physique, Centre universitaire

de Khenchela, Algérie. C. Harkati, and R. Halimi. Laboratoire Couches Minces et Interfaces, Département

de Physique, Faculté des Sciences, Université Mentouri, 25000 Constantine, Algérie.

Hard chromium carbide coatings were elaborated by depositing a chromium layer ( 3μm or 1 μm

thickness ), using the physical vapour deposition technique of magnetron sputtering, on carbon steel

substrates and, subsequently, annealing the system in vacuum at temperatures from 200°C to

1200°C. Structural characterization was assessed using scanning electron microscopy and X-ray diffraction.

Some mechanical properties such as micro and nano-hardness and residual stresses were

studied. It was found that the binary carbides Cr 7 C 3 , and Cr 23 C 6 appear at 700°C and 900°C respectively.

The Cr 7 C 3 compound transforms then at 1000°C into ternary carbide (Cr,Fe) 7 C 3 . It was

showed that the micro and nano-hardness increase with the rising of annealing temperature until

reaching a maximum value and then decreases. The increase of the hardness is associated to the

chromium carbides formation, which are harder. However, its decrease is due to the iron atoms diffusion

into the coating layer. Thicker Chromium coatings present a better adhesive properties. It is,

also, observed that the compressive residual stresses in coating (σ ϕ = -734 MPa at 900°C) become

tensile at 1000°C (σ ϕ = 127 MPa).

Keywords: Chromium, coating, carbides, thin films

Presenting author: L. AISSANI

E-mail: lindaaissani2004@yahoo.fr

Presentation type: Poster

134


JUNE 28 WEDNESDAY AFTERNOON

JS2-WeA-P.1 IMPROVEMENT OF MECHANICAL PROPERTIES OF STEEL

SUBSTRATES SURFACE BY DEPOSITION OF THIN TITANIUM FILMS OBTAINED BY

MAGNETRON SPUTTERING METHOD. R. Gheriani. Physical laboratory of Materials, University

of Ouargla , 30.000- Algeria. R. Halimi. Unity of research, Materials and applications, University

of Constantine, 25.000 – Algeria.

Titanium carbides are well known materials with great scientific and technological interest. The applications

of these materials take advantage of the fact that they are very hard, refractory and that

they have metallic properties.

In this work, We have studied the influence of the heat treatment temperatures ( 400-1000°C) on the

interaction between the titanium thin films and steel substrates. Steel substrates, 100C6 type (AF-

NOR norms), containing approximately 1 wt % of carbon, were coated at 200°C with titanium thin

films by magnetron sputtering.

The samples were characterized by X ray diffraction (XRD), Auger electron spectroscopy (AES) and

scanning electron microscopy (SEM). Vikers micro-hardness measurements carried out on the annealed

samples showed that the micro-hardness increases with annealing temperature, reaches a

maximum (3500 kg/mm 2 ), then decreases progressively. The growth of micro-hardness is due to the

diffusion of the carbon, and to the formation of titanium carbide. However, the decrease of microhardness

is associated to the diffusion of iron and the formation of iron oxide (Fe 2 O 3 ). At higher

temperatures, we note the formation of titanium oxide (TiO 2 ).

133


JS2 POSTERS

132


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.8 ON THE INFLUENCE OF TE EXCESS ON THE OPTICAL PROP-

ERTIES OF VACUUM EVAPORATED ZNTE THIN FILMS. P. Prepeliţă, M.Rusu, C.Baban,

G.I.Rusu. Faculty of Physics “Al. I. Cuza” University, B-dul Carol I, No.11, Iasi, Romania. (e-mail:

prepelita@stoner.phys.uaic.ro)

ZnTe thin films are intensively studied due to their interesting properties such as high transmission

coefficient, large energy bandgap, low electrical resistivity, etc. An important factor that influences

the properties of these films is the deviation from their stoichiometric composition. In present paper,

the influence of tellurium excess on the optical properties of evaporated ZnTe thin films is investigated.

The studied films (d = 0.700 µm - 1.300 µm) were deposited onto unheated glass substrates by

evaporation under vacuum of ZnTe powder at source temperature ranged between 900 K and 1200

K. The structural analysis of the films was performed by XRD and AFM techniques. The optical parameters

(refractive index and absorption coefficient) both for as deposited and heat treated samples

were determined from transmission spectra in the spectral range 340 nm - 1400 nm.

It was found that the studied films present a polycrystalline zinc blende structure with preferential

orientation of (111) planes parallel to the substrate. An excess of tellurium atoms which aggregate in

crystallite form during film annealing was observed. This Te excess determines a significant increase

of the absorption coefficient near the fundamental absorption edge and of refractive index in the infrared

domain. Depending on Te content, the optical bandgap energy, E g , calculated from the absorption

spectra, ranged between 1.9 eV and 2.4 eV.

The results are discussed in correlation with film structure and the impurity levels introduced by the

Te excess.

131


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.7 UHV REACTIVE EVAPORATION GROWTH OF TITANIUM NI-

TRIDE THIN FILMS, LOOKING FOR MULTIPACTOR EFFECT SUPPRESSION IN

SPACE APPLICATIONS. Ana Ruiz and Elisa Román. Instituto de Ciencia de Materiales de Madrid.

Consejo Superior de Investigaciones Científicas. Cantoblanco. E-28049-Madrid. Spain Pilar

Lozano*, Mariano García and Luis Galán. Departamento de Física Aplicada. Universidad Autónoma

de Madrid.Cantoblanco. E-28049 Madrid. Spain. Isabel Montero. Instituto de Ciencia de Materiales

de Madrid. Consejo Superior de Investigaciones Científicas. Cantoblanco. E-28049-Madrid. Spain.

David Raboso. ESA/ESTEC. Keplerlaan, 1. 2200 AG Noordwijk. The Netherlands.

A low secondary electron emission yield which remains stable after exposure to ambient, as well as a

good electrical conductivity, have proved to be basic criteria for selecting a reliable coating in RF

components for space applications, in order to reduce the multipactor effect. Although titanium nitride

is among the most appropriate materials, its actual performance is very much dependent on the

deposition conditions. Standard deposition techniques used for TiN thin films or coatings often produce

layers that are far from optimal, specially concerning secondary emission yield and its stability

when exposed to air.

In this work, an ultra-high vacuum reactive evaporation procedure has been tested and optimized for

the growth of TiN thin films, throwing very good results both in composition of the TiN layers and

SEY values and performance. Sublimation of Ti filaments is carried out in a ultra-high vacuum

chamber in which a controlled leak of high purity N 2 is placed close to the substrate surface, thus

maintaining the overall pressure in the high vacuum range and preventing nitridation of the Ti filaments.

Detailed description of the growth procedure, substrate preparation and deposition protocol

will be described with special emphasis on the relevant growth parameters and practical hints and

how to achieve them. We present a study of the samples grown, such as stoichiometry and composition

obtained by means of XPS and AES, and secondary electron emission measurements versus

time in the scale of several months. The results obtained show that the deposition technique throws

the best results towards the multipactor effect suppression.

*present address: Instituto Universitario de Investigación en Nanociencia de Aragón. Universidad de

Zaragoza.

Edificio Interfacultativo II. c/ Pedro Cerbuna,12.E-50009 Zaragoza (Spain)

130


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.6 DC-PULSED PLASMA NITRIDING (DCPPN) OF STANLESS STEEL:

MICROSTRUCTURE, CORROSION A WEAR BEHAVIOUR. P. Corengia 1 , E. De Las

Heras 2 , M. Brizuela 1 , D. González 1 , A. García-Luis 1 , G. Ybarra 2 , C. Moina 2 . 1 Fundación INASMET-

Tecnalia, Paseo de Mikeletegi 2, 20009 San Sebastián, Spain. 2 Instituto Nacional de Tecnología Industrial,

Av. Gral. Paz 5445, C.C. 157, (B1650 WAB) San Martín, Argentina.

Stainless steels are usually employed as engineering materials due to high corrosion resistance.

However, low wear resistance and poor tribological behaviour limit their use in some industrial applications.

Therefore, there is an increasing interest in improving surface properties through plasma

assisted treatments, notably ion nitriding. Although stainless steels can be nitrided with the consequential

increase in surface hardness, which improves their tribological performance, this is accompanied

by a loss of corrosion resistance of the nitrided case. Nitriding of stainless steels leads to a

depletion of chromium content in the matrix, thus reducing the corrosion resistance of the nitrided

layer.

In the present work, industrial-scale DC-pulsed plasma nitriding for 20 h at 673K was used to improve

the surface properties of both martensitic (AISI 410) and austenitic (AISI 316L) stainless

steels. The effect of nitriding on structural and mechanical properties of the nitrided layer was investigated

by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and

microhardness.

The tribological behaviour was studied and compared to the behaviour of the same steel in asreceived

condition. The wear resistance was investigated using an Amsler-disc-machine, employing

a dry combined contact of rolling–sliding with three different applied loads. The wear mechanisms

involved during the test of unnitrided and plasma nitrided steels were investigated by microscopic

observation of the surfaces, the corresponding cross-sections and the produced wear debris. In addition

microhardness profiles were done in order to evaluate the work hardening effect during the wear

process. Electrochemical experiments in 3% NaCl solution were carried out to characterize the corrosion

behaviour of unnitrided and nitrided stainless steels.

Analysis and discussion of the tribological results show that plasma nitriding improves the wear resistance

of the surface on stainless steels and the main wear mechanism appears to be delamination.

Consequences on the load bearing capacity are discussed.

The modified layers of the nitrided AISI 316L steel were composed of “expanded austenite”, while

the nitrided AISI 410 samples were characterized by the presence of “expanded ferrite”, CrN and

Fe 4 N.

The DCPPN samples of both AISI 316L and AISI 410 revealed a surface hardness above 1000 HV

and a sharp interface between the case (nitrided layer) and the core (matrix).

Results of electrochemical measurements of unnitrided and DCPPN specimens were analysed and

related to the microstructural characteristics of the nitrided case.

Corresponding author: Tel: +34 943 003700; fax: +34 943 003800, e-mail:

pablo.corengia@inasmet.es

129


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.5 PHOTOLUMINESCENCE OF RHODAMINE 6G DOPED AMOR-

PHOUS TIO 2 THIN FILMS GROWN BY SOL-GEL. R. Palomino-Merino 1 , J. Torres-

Kauffman 1 , R. Lozada-Morales 1 , and O. Portillo-Moreno 2 , Benemérita Universidad. Autónoma de

Puebla. 1 Posgrado en Optoelectrónica, Facultad de Ciencias Físico-Matemáticas. 2 Facultad de Ciencias

Químicas. México. M. García-Rocha, and O. Zelaya-Angel. Department of Physics. Centro de

Investigacion y de Estudios Avanzados del IPN. P.O. Box 14-740, Mexico 07360 D.F.

Rhodamine 6G doped amorphous titania thin films were prepared by the sol-gel technique. The films

were grown at room temperature and supported on silica-glass substrates which were previously

chemically activated. Photoluminescence (PL) spectra were registered at room temperature by using

as photoexcitation the 325 nm He-Cd line. The PL versus the photon energy emission curves peak at

around 3.2 eV, which open the possible application of this material for solid state UV laser devices

fabrication.

128


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.4 PHOTOLUMINESCENCE AND BAND-SPLITTING IN CDS THIN

FILMS, INFLUENCE OF CDCL 2 AND THERMAL ANNEALING. O. Vigil-Galán, G.

Contreras-Puente, and J. Aguilar-Hernández. Escuela Superior de Física y Matemáticas, Instituto Politécnico

Nacional, México 07738 D.F. J. Vidal-Larramendi, and A. Arias-Carbajal. Univ. de la Habana,

43100, La Habana, Cuba. O. Zelaya-Angel. Departamento de Física, CINVESTAV-IPN, P.O.

Box 14-740, México 07360 D. F.

CdS thin films were deposited on conducting glass substrates by three different techniques: (a)

chemical bath deposition (CBD), (b) close spaced vapor transport (CSVT), and (c) laser ablation

(LA). As-grown and coated with CdCl 2 CdS-samples were thermal treated (TT) in Ar. From optical

absorption measurements the valence band splitting in cubic and hexagonal layers are observed (in

CBD and CSVT films). In the case of CdS films grown by CSVT the hexagonal wurtzite (W) crystalline

phase is observed in as-grown and TT samples, while using CBD as-grown and annealed CdS

films are cubic zincblende (ZB). For LA-CdS samples no band splitting was observed in both asgrown

and annealed samples, these two types of LA-CdS layers have W as crystalline phase. Band

splitting is characterized for the variation of the energy band gap (E g ) shift (ΔE g ) due to the spin-orbit

*

*

interaction with ΔE g = 0.069 eV, where ΔE g → Δ E g

when ZB → W, with Δ E g

= 0.081 eV, the

change is owing to the reordering of splitting levels because of the addition of the crystal field interaction.

The evolution of the crystalline quality and the ΔE g change in the three kinds of grown films,

beside optical absorption measurements, was studied from photoluminescence spectra

127


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.3 OPTICAL CHARACTERIZATION OF VACUUM EVAPORATED

CdZnTe THIN FILMS DEPOSITED BY STACKED LAYER METHOD. G.G. Rusu, M. Rusu,

M. Girtan. Faculty of Physics, “Al.I. Cuza” University, B-dul Carol I, No. 11, Iasi, Romania (e-mail:

rusugxg@uaic.ro)

The interest in the study of CdZnTe (CZT) alloys in thin films has been increased due to their important

applications in technology of thin film devices as solar cells, photo-detectors, gamma-ray detectors,

etc.

Among other preparation techniques of CZT, the physical vapour deposition is often preferred. In

such method, the evaporation of CdTe and ZnTe mixed powder or co-evaporation from dual CdTe

and ZnTe sources are frequently used. An inconvenient of these procedures is the difficulty to control

of Zn content in as evaporated CdZnTe films due to the vapour pressure difference between

CdTe and ZnTe and to the lower sticking coefficient of Zn.

To avoid this inconvenient, in present paper, a modified two source evaporation technique was used

to prepare CdZnTe thin films. Namely, during film deposition, the film substrates, placed onto a rotating

disk, passed successively with constant rate over the CdTe powder and metallic Zn evaporation

sources respectively, separated between them by two glass cylinders. In this way, nanolayered

CdTe/Zn structures with uniform Zn content were deposited. The structural and optical properties of

as deposited CdZnTe films were investigated.

Depending on the preparation conditions, both quasi-amorphous and oriented (111) polycrystalline

films were obtained. Also, depending on Zn content and heat treatment, the value of optical band

gap, E g , for studied films ranged between 1.48 eV and 1.63 eV.

126


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.2 STUDY OF OPTICAL PROPERTIES OF DIAMOND LIKE CARBON

/POROUS SILICON ANTIREFLECTION COATING LAYERS FOR MULTICRYSTAL-

LINE SILICON SOLAR CELL APPLICATIONS. K. Ait-Hamouda. Labo Instrumentation,

Faculté d’Electronique et informatique, USTHB, BP 32 El-Alia Bab-ezouar Alger, Algérie. M.

Ouchabane. CDTA , Haouche Loukil BP17, Baba-Hassen Alger, Algérie. A. Ababou. Labo Instrumentation,

Faculté d’Electronique et informatique, USTHB, BP 32 El-Alia Bab-ezouar Alger, Algérie.

N. Gabouze. UDTS, 2Bd Frantz Fanon BP 399, Alger Algérie

In the past decade, Diamond Like Carbon (DLC) coatings have received great attention essentially

due to their unique properties such as mechanical hardness, adhesion strength and chemical inertness,

and recently in the sensing application, combined with porous silicon. In addition, the same

research group demonstrates an enhancement of the photoluminescence of the porous layer subjected

to a DLC layer deposition.

In this work, we report a study on some optical properties of DLC films. The DLC films have been

deposited by DC discharge plasma enhanced chemical vapor deposition. The deposited layers have

been characterized by spectrophotometry, ellipsometry and FTIR analysis.

The evolution of optical properties for different DLC thickness layers has been correlated with the

FTIR spectra change. In addition, The DLC films have been deposited on multicrystalline solar cell

with a PS film (< 0.3 μm) as an antireflection coating. The results reveal that the solar cell efficiency

strongly depends on the DLC layer thickness. The quantum efficiency of the solar cell coated with a

DLC layer increases by 5% order than the uncoated cell.

125


JUNE 28 WEDNESDAY AFTERNOON

JS1-WeA-P.1 γ N -SHIFTING AS A FUNCTION OF N 2 CONTENT IN AISI 304 NI-

TRIDING. R. Valencia-Alvarado a , A. de la Piedad-Beneitez , J. de la Rosa-Vázquez , R. López-

Callejas , S. R. Barocio , O. G. Godoy-Cabrera , A. Mercado-Cabrera , R. Peña-Eguiluz and A.

E. Muñoz-Castro. Instituto Nacional de Investigaciones Nucleares, Plasma Physics Laboratory, A

P. 18-1027, 11801 México, D.F. Instituto Tecnológico de Toluca, AP 890, Toluca, México. Instituto

Politécnico Nacional, ESIME, 07738, México, D.F. a E-mail: rva@nuclear.inin.mx

We present in this work some experimental results obtained from nitriding AISI 304 stainless steel at

different temperatures by means of RF/DC generated 10 15 -10 16 m -3 density plasmas in the 1-4 eV

temperature range. The samples were biased up to –500 V. Substrate temperatures proof to be an

influential factor in the diffusion of the impinging ions into the material under treatment. In turn,

this temperature during the expanded γ N shift, is a function of the amount of nitrogen introduced to

the sample given by the bias, the depth of the nitrided layer and the plasma characteristics. Thus, we

have chosen the substrate temperature as a global control variable in order to analyze the evolution

of the nitrogen enrichment process through its influence on the X ray diffraction imaging of the γ N

shift in the samples. The optimization of the temperature is explored along with its limits in terms of

the Cr precipitation threshold.

124


JS1 POSTERS

123


JUNE 28 WEDNESDAY AFTERNOON

RIVA-TF-WeA-P.7 GROWTH OF CRYSTAL GERMANIUM-CARBIDE BY IMPLAN-

TATION . Genene Tessema 1,2 1 Faculty of Science, Department of Physics, Addis Ababa University,

P.O.BOX 1176, Addis Ababa, Ethiopia. 2 Helmholtz-Institut für Strahlen und Kernphysik, Nussalle

14-16, 53115 Bonn, Germany

The interactions of carbon with probe nucleus 111 In have been studied in germanium using the perturbed

angular correlation (PAC) method, which has the ability to detect the microscopic environments

of the probe atom by means of the interaction of the nuclear moments of the probe and the surrounding

electromagnetic fields 1,2 . At high dose carbon implantation in germanium two complexes

have been identified by their unique quadrupole interaction frequencies. An interaction frequency of

ν Q = 207(1) MHz (η = 0.16(3)) appeared at annealing temperatures below 650 ο C. Above 650 ο C, it

was replaced by a second interaction frequency of ν Q = 500(1) MHz ( η= 0). The frequencies are attributed

to two different carbon-indium pairs. The orientation of the corresponding electric field gradients

and thermal stability of the defect complexes are studied. The results are found to be in good

agreement with other methods 3 .

1. Th. Wichert, M. Deicher, G. Grübel, R. Keller, N. Schulz and H. Skudlik, Appl. Phys. A 48, 59

(1989)

2. G. Schatz and A. Weidinger, Nuclear Condensed Matter Physics, John Wiley and

Sons, New York (1992)

3. L. Hoffmann, J. C. Bach, and B. Bech Nielsen, Phys. Rev. B ; Vol. 55(17), 11 167 (1997)

122


JUNE 28 WEDNESDAY AFTERNOON

RIVA-TF-WeA-P.6 AgInTe 2 CHALCOPYRITE THIN FILMS OBTAINED BY

ELECTRODEPOSITION TECHNIQUES AND ANNEALING. R. Díaz, F. Rueda Dpto. Física

Aplicada Universidad Autónoma de Madrid, 28049 Madrid, Spain. P.Herrasti, E. Vazquez Dpto. Química

Física Aplicada Universidad Autónoma de Madrid, 28049 Madrid, Spain. M. Abd el Lefdil Dpt

de Physique, Université de Rabat, Maroc

In order to obtain single phase thin films of the system Ag-In-Te for thin film solar cell applications,

electrodeposition techniques followed by a baking in Te atmosphere were used. For the formation of the

precursor films three alternative processes were followed, 1t) the co-electrodeposición of Ag and In, 2d)

a layer of Ag with an overlayer of InTe and 3d) a layer of Ag and an overlayer of In. The vacuum

annealing were done with a source of Te metal close to the films that allowed to crystallize into ternary

chalcopyrite phase the as deposited amorphous films. Bath compositions, deposition potentials and

deposition times have been changed to obtain the precursor thin films on substrates of molybdenum

supported by glass. In order to determine the optical properties, SnO 2 coated substrates were also used.

The single phase films are obtained by further annealing in Te atmosphere in the 250-400 o C range with

different cooling profiles. This annealing strongly affects the Te concentration as well as the In/Ag

atomic ratio and the number of phases. Single chalcopyrite phase has been obtained for specific

annealing conditions and is related to Te concentration.

Composition and X-ray studies have been carried out and several phases of AgInTe 2 and In-rich

Telluride chalcopyrites have been found. The film morphology and unit cell parameters for single

phase samples depend strongly on the composition in the annealed samples.

The support of contract No CTQ2005-04469/BQU is acknowledged

121


JUNE 28 WEDNESDAY AFTERNOON

RIVA-TF-WeA-P.5 VAPOUR SOURCE WITH SUBMONOLAYER CONTROL. H. P.

Marques, A. R. Canário, O. M. N. D. Teodoro and A. M. C. Moutinho. CEFITEC, Departamento de

Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 CAPARICA,

Portugal

To achieve highly accurate controlled depositions a specially designed vapour source was developed.

It provides direct rate and thickness monitoring with submonolayer control.

This compact dosing system basically consists of an evaporation source, a quartz crystal microbalance

and a shutter. The source was intended to evaporate metals with low to medium melting temperature.

It was tested with a high purity Ag wire (99.99%) wrapped around a tungsten filament. Resistive

heating was provided by an adjustable constant current through the filament.

The microbalance and the surface are mounted on the same line with the filament in between. The

careful geometric configuration and distances of the microbalance, filament and surface are such that

only 1/10th of the amount of metal deposited on the quartz crystal is deposited on the sample surface.

Therefore the resolution of the microbalance is extended by one order of magnitude.

The direct thickness measurement by the quartz microbalance with factory parameters was checked

in a calibration experiment. For the calibration an Ag film was deposited on polycrystalline Au surface

and the growth followed with LEIS. The break at the monolayer formation was used to calibrate

the thickness measurements.

This source is being successfully used to study the growth of Ag clusters on TiO 2 . The deposition

rate is a known parameter to control the size of the nanoclusters. During the depositions the mechanical

shutter provides an accurate vapour blanking to the surface. The typical dosing rate may be

as low as 0.035 ML/min, where 1 ML corresponds to 1.4x10 15 atoms.cm -2 .

120


JUNE 28 WEDNESDAY AFTERNOON

RIVA-TF-WeA-P.4 NITROGEN-DOPED TiO 2 THIN FILMS DEPOSITED ONTO

ITO/GLASS SUBSTRATES. Diana Mardare. Al.I.Cuza University, Faculty of Physics, Carol I

Blvd., No.11, Iasi 700506, ROMANIA. Luca Dumitru. Al.I.Cuza University, Faculty of Physics,

Carol I Blvd., No.11, Iasi 700506, ROMANIA

Titanium dioxide films are extensively used in optical thin film device applications owing to their

appropriate optical properties, high thermal and chemical stability in hostile environments. These

films present good durability, a high transmittance in the visible spectral range, and a high refractive

index, so that they are suitable for applications, such as: antireflection coatings, multilayer optical

coatings (used as optical filters), optical waveguides, etc. Also, TiO 2 has focussed a considerable attention

in the past decades as a material with a strong oxidation power, being considered one of the

best photocatalytic material which can be used in order to solve some of the world environmental

problems.

Titanium oxide crystallizes in three different forms: anatase (tetragonal), rutile (tetragonal) and

brookite (orthorhombic) and may also exist in an amorphous state. Rutile is a denser phase than anatase

and brookite, being also the most thermodynamically stable. By changing the deposition parameters,

by performing a heat treatment, or by doping with different impurities, the ratio of the

mentioned phases changes, leading to changes in optical and electrical properties of titanium oxide

thin films [1-3]. The three phases are characterized by different optical properties and determine different

transmittances, optical constants and optical band gaps of the thin films. The catalytic properties

are connected with the large band gap value of the anatase phase (3.2 eV) associated with a low

recombination rate of the charge carriers generated in the surface area by the incident photons.

Undoped and nitrogen-doped titanium oxide films were prepared by reactive magnetron sputtering

onto ITO/glass substrates. Film structure and surface morphology were investigated by X-ray diffraction

and atomic force microscopy. X-ray diffraction (XRD) studies revealed an amorphous structure

of the as-deposited thin films. The surface roughness was derived from AFM imaging. By heat

treatment the amorphous films became polycrystalline. The heat-treated-nitrogen-doped films have a

pure anatase structure, while the undoped ones contain only the rutile phase.

The contact angle of the deionized water with film surface was monitored during both photoactivation

and recovery regimes. The results are discussed in terms of the effects of surface roughness and

of rutile-anatase TiO 2 phase transformation induced by heat treatment and by nitrogen doping, as reflected

in optical transmittance results.

[1] D. Mardare, M. Tasca, M. Delibas and G. I. Rusu, Appl Surf Sci 156 (2000) 200.

[2] A. R. Bally, E. N. Korobeinikova, P. E. Schmid, F. Lévy and F. Bussy, J Phys D: Appl Phys 31

(1998) 1149.

[3] D. Mardare and P. Hones, Mater Sci Eng B 68 (1999) 42.

119


JUNE 28 WEDNESDAY AFTERNOON

RIVA.TF-WEA-P.3 ON THE PHYSICAL PROPERTIES OF PENTACENE THIN FILMS.

Mihaela Girtan a,b Sylvie Dabos – Seignon a , J.M. Nunzi a . a Laboratoire POMA, UMR CNRS 6136,

Université d’Angers, 2 Bd. Lavoisier, 49045 Angers cedex, France, email: mihaela.girtan@univangers.frb

Faculty of Physics, Al.I. Cuza University of Iasi, Romania

Pentacene thin films with thickness ranged between 50 nm and 200 nm were deposited by vacuum

thermal evaporation on glass and ITO substrates at room temperature. The rate of deposition was

about 0.14 nm/s. The influence of substrate nature and films thickness on the film morphology was

investigate by atomic force microscopy (AFM). Electrical and optical investigations were correlated

with the structural and morphological analyses.

118


JUNE 28 WEDNESDAY AFTERNOON

RIVA-TF-WeA-P.2 PHOTOCATALYTIC DEGRADATION OF COMMERCIAL DYES

USED IN THE TEXTILE INDUSTRY BY THE DEPOSITION TiO 2 THIN FILMS ON

GLASS SUBSTRATES. S.M. Marques 1 , C.J. Tavares 1 , V. Teixeira 1 , J.O. Carneiro 1 , A.J. Fernandes

2 .

1 Departamento de Física, Universidade do Minho, 4800-058 Guimarães, Portugal.

2 Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal

ctavares@fisica.uminho.pt

The interest in nanoparticle photocatalytic titania (TiO 2 ) thin films has been increasing over the last

few years, due to the self-cleaning nature of these coatings. They have been used on industrial applications,

mainly due their ability to degrade pollutants dissolved in water. Titania acts as a photocatylist

for the dissociation of organic impurities on a particular surface, such as glass. The driving

force behind this photocatalisation is simply ultraviolet (UV) light and atmospheric oxygen. The thin

films of titania were deposited by unbalanced reactive magnetron sputtering, from a high purity Ti

target in an Ar/O 2 atmosphere, with an argon flow rate of 60 sccm (working gas) and a variable oxygen

flow rate in he range of 1.5-9 sccm (reactive gas). Due to the fact that the deposition temperature

is rather low (≈ 200ºC), the titanium dioxide particles that nucleate on the substrate do not have sufficient

energy and mobility to crystallise in a regular lattice, such as Brookite, Anatase or Rutile. In

order to achieve this thermodynamical equilibrium and enhance the composition between the crystallographic

phases, after deposition the samples were thermally annealed in a high vacuum furnace at

different temperatures, 300ºC, 400ºC and 500ºC for 2 hours. In order to comprehend the underlying

structure, X-ray diffraction measurements were then preformed in these heat treated samples and the

composition of the films was study by Rutherford Backscattering spectroscopy (RBS). We also estimated

the thickness of the films made with different flow rates of oxygen and with different times of

deposition, using the Swanepoel’s method for the calculation of the optical properties of the coatings.

The photocatalytic behaviour of the titania coatings was assessed by combined ultra-violet irradiation

and absorption measurements of particular dyes. The observed photo-decomposition of the

aqueous solution (organic pollutants) was measured in the UV/Vis Spectrum by the decrease of the

maximum absorbance with irradiation time. The colour of the dye becomes colourless during this

process, hence indicating that the chemical oxidation-reduction mechanisms abound on the surface

of the titania films. As pollutants, we used dyes that are currently used in the textile industry, as it is

the case of the reactive dye “RED 41”.

117


JUNE 28 WEDNESDAY AFTERNOON

RIVA-TF-WeA-P.1 SEM AND XPS ANALYSIS OF POLYCRYSTALLINE GAN FILMS

GROWN BY CYCLIC PULSED LASER DEPOSITION. P. Sanguino 1 , R. Schwarz 1 . 1 Departamento

de Física, Instituto Superior Técnico, Lisboa, Portugal M. Wilhelm 2 , M. Kunst 2 2 Hahn-

Meitner-Institut, Solare Energetik, Berlin, Germany O. Teodoro 3 Departamento de Física, Universidade

Nova de Lisboa, Monte de Caparica, Portugal

We describe a detailed study of Scanning Electron Microscopy (SEM) combined with Energy Dispersive

Spectroscopy (EDS) analysis to study composition and structure of 500 nm thick polycrystalline

GaN samples. The films have been deposited by Cyclic-Pulsed Laser Deposition (Cyclic-PLD)

with a Nd:YAG nanosecond pulsed laser at 1064 nm. SEM pictures of the GaN layers revealed a

structure composed of grains with typical dimensions of 200 nm. Coalescence of the grains was

more evident for a 1 m thick sample. EDS mapping of the GaN layer was performed for Ga, N, O,

and Al and could be related with the corresponding SEM scan. Both EDS and XPS composition

analysis pointed to a Ga rich (or N deficient) GaN layer.

116


RIVA-TF POSTERS

115


JUNE 28 WEDNESDAY AFTERNOON

RIVA-SS-WeA-P.3 ELECTRON STIMULATED DESORPTION STUDY OF DEFCT

SITES ON THE MgO(100) SURFACE USING QUADRUPOLE MASS SPECTROMETRY

AND TIME OF FLIGHT. I. Colera * , J. L. de Segovia ** , D. Cáceres * , E. Román ** and R. González

* . * Departamento de Física. Universidad Carlos III de Madrid. Leganés. 28911 Madrid. Spain. **

Laboratorio de Física e Ingeniería de Superficies. Instituto de Ciencia de Materiales.

CSIC.Cantoblanco. 28049 Madrid. Spain

While the quadrupole mass spectrometer (QMS) is an excellent tool to identify desorbed ions and

energy thresholds in electron stimulated desorption (ESD) experiments, its analysis of the ion kinetic

energy distribution is questionable. However, time of flight (TOF) is an excellent technique to

analyse the ion energies by using the QMS as the driving tube for the time of flight. The simultaneous

use of the ESDQMS and ESDTOF techniques yields excellent results in the determination of the

ion nature, ion threshold, and ion energy distribution in the study of site defects of on the MgO(100)

surface. Defect sites are identified by exposing the MgO(100) surface to D 2 O and H 2 18 O. Thus, the

D and 18 O can be differentiated from the 16 O and H surface atoms. The energy of the exploring electrons

varied from 200 to 600 eV, and an intensity of 100 nA was used to avoid surface damage. The

sample charge was also studied as a function of the incident electron en energy.

114


JUNE 28 WEDNESDAY AFTERNOON

RIVA-SS-WeA-P.2 SECONDARY ELECTRON EMISSION YIELDS OF EXTER-

NAL DIELECTRIC COATINGS USED IN SPACE . Isabel Montero, Ainhoa Pardo, Pablo

Rios and José Luis de Segovia. Instituto de Ciencia de Materiales de Madrid. CSIC. Cantoblanco.

28049-Madrid. Spain. Luis Galán. Universidad Autónoma de Madrid. Cantoblanco. 28049-Madrid.

Spain. Léon Lévy. Office National d'Etudes et de Recherche Aerospatiales, 2 Avenue Edouard Belin,

31055 Toulouse, Cedex 4, France. Marc Van Eesbeek. European Space Research and Technology

Centre (ESTEC), European Space Agency (ESA), Keplerlaan 1, PO Box 299, NL-2200 AG Noordwijk,

The Netherland

Within ESA Program, AO4136 “Material Characterisation for Plasma Interaction Analysis”, headed

as prime contractor by ONERA, our group from ICMM (CSIC) and UAM has been developing a research

on secondary electron emission and photoemission properties of reliable insulator materials to

study their charging behaviour in space.

The spacecraft surface potential is a function of the net current flow to or from the spacecraft surface.

Electrons impinging on the spacecraft can produce secondary electron emission. Photoemission

from the extreme ultraviolet photon range is the most important since in that region many materials

have rather large photoelectric yields and the solar spectrum also has significant energy there. This

work presents results on secondary electron emission and photoemission yields of space used external

dielectric coatings. The dielectric materials studied was polymers: kapton, betacloth and upilex,

and doped silicon glasses: CMX and CMO.

The total secondary electron emission coefficient, σ, per primary electron, versus primary energy,

Ep, curve was characterized by the following parameters: σm the maximum value and the corresponding

primary energy Em, and the two crossover energies: E1, the lowest Ep for σ =1, and E2 the

highest Ep for σ =1. The beam pulsing measuring technique was used in order to reduce or avoid the

charge incorporation into the samples. SEY was measured for normal incidence and as a function of

primary electron energy. Current pulses of 0.1 -1 μs of low intensity (1nA-50 nA) were used to reduce

the electron dose received by the sample (≤106electrons/pulse). For each primary energy, the

sample was bombarded with only one current pulse. Surface charge decay occurs immediately when

the e-irradiation is stopped, but it depends on the discharging time constants. After each measurement,

the charge of the sample was removed: the trapped charge was liberated with the mercury

lamp (negative surface charging) and the flood-gun (positive surface charging). Analysis of the coatings

was performed, apart from SEY and PES measurements, by XPS (X-ray Photoemission Spectroscopy),

SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-ray Spectroscopy) and

UVS (Ultraviolet spectroscopy).

113


JUNE 28 WEDNESDAY AFTERNOON

RIVA-SS-WeA-P.1 TiCr ALLOYS OF LOW SECONDARY ELECTRON EMISSION

FOR ANTIMULTIPACTOR APPLICATIONS. G. G. Fuentes and R. J. Rodríguez, AIN-Centro

de Ingeniería Avanzada de Superficies, Cordovilla, 31191, Pamplona, Spain. L. Galán, Departamento

de Física Aplicada. Universidad Autónoma de Madrid. Cantoblanco. 28049-Madrid. Spain. I.

Montero and J. L. Segovia, Instituto de Ciencia de Materiales de Madrid. CSIC. Cantoblonco.

28049-Madrid. Spain

TiCr alloys of low secondary electron emission have been investigated as potential anti-multipactor

coatings. Cathodic-arc evaporation technique in Ar atmosphere was used. The ion energy can be

controlled by the substrate biasing. Chemical state analysis and surface composition were obtained

by X-ray Photoemission Spectroscopy (XPS). Depth profiling was performed by Glow Discharge

Optical Emission Spectroscopy (GDOES). Scanning Electron Microscopy images show the formation

of grains on the surface. The film composition is homogeneous, however, the composition of the

grains varied with their size. Larger grains are richer in titanium, while small ones are rich in chromium

as indicated by energy Dispersive X-ray analysis. Total secondary electron emission yield was

determined by measuring the sample current to ground when bombarded by a primary electron beam

of determined energy. The secondary electron emission coefficient of TiCr alloy exposed to air was

lower than those of chromium or titanium coatings and their nitrides. The experimental secondary

emission yield values together with a Montecarlo model of the secondary emission process were

used to obtain the multipactor threshold.

112


RIVA-SS POSTERS

111


WENESDAY AFTERNOON

POSTER SESSIONS

110


JUNE 28 WEDNESDAY MORNING

WS-18-WeM-INV.12 THE EFFECT OF MECHANICAL AND FRICTIONAL PHE-

NOMENA ON THE QUALITY OF VACUUM IN ADVANCED TECHNOLOGIES. R.A.

Nevshupa. Department of Vacuum Mechanics and Tribology (MT-11), Bauman Moscow State

Technical University, 2-Baumanskaia 5, Moscow 105005, Russia. J.L. de Segovia, E. Roman. Department

of Surface Physics and Engineering, Institute of Material Science of Madrid, C/ Sor Juana

Ines de la Cruz 3, Cantoblanco, Madrid 28049, Spain

By the last quarter of the twentieth century, as the result of several progresses in materials, coatings,

degassing procedure, and pumping technologies, attaining of extremely high vacuum below 10 -8 Pa

had became almost routine task in many technologies ranging from electronic and optoelectronic industries

to large particle accelerators and physical experimental systems. These progresses allowed

to control precisely desorption of gases from stationary surfaces faced to vacuum and to obtain specific

desorption rate from these surfaces below 10 -8 Pa·m 3·m -2·s -1 . In this circumstances secondary

desorption phenomena come to the foreground to provide quality of the total and partial pressures in

technological systems. Tribodesorption, i.e. desorption of gas stimulated by mutual friction, indentation

and other types of mechanical action, is one of the most important among these desorption phenomena

due to high desorption yield and abundance of moving parts in modern ultrahigh vacuum

technological equipment. Specific desorption rate during sliding of stainless steel, other metals and

tribological coatings can be as high as 10 -2 - 10 -3 Pa·m 3·m -2·s -1 . Although contact area, which molecules

are desorbed from, is usually very small, instant pressure increase due to translation of moving

parts inside vacuum system can be of the order of 10 -6 - 10 -7 Pa that is critical for many technological

processes. Moreover, friction is a source of hydrocarbons, carbon oxides, water vapours and other

contaminating substances, which might harm sensitive production.

Tribodesorption is a complex phenomenon based on three main physical sources: desorption of the

topmost adsorbed gas layers, emission of gas molecules from the shallow subsurface zones and tribochemical

reactions. In high and ultrahigh vacuum the late two sources are dominating. The composition

of desorbed gas depends on many factors including kind of material, content of the gas in

the material, presence of adsorbed phases and so on. Time behaviour of tribodesorption has maximum

at the beginning of friction of fresh surface and slowly decreases during friction. However, tribodesorption

rate can be restored after resting time during 12 or more hours or after moderate heating

of the rubbed surface. These facts point the diffusion of gas atoms and molecules in the material

bulk as a precursor of tribodesorption.

In addition, tribodesorption is strongly correlated with any damage of the surface, i.e. plastic deformation,

fracture, cracking, wear and so on. This feature is very promising for developing of reliable

tribological coatings for vacuum applications.

109


JUNE 28 WEDNESDAY MORNING

WS-18-WeM-INV.11 QA EFFORTS IN MANUFACTURING LARGE CRYOPUMP

SYSTEMS FOR NUCLEAR FUSION APPLICATION. Hans S. Jensen and Chr. Day. Institute

for Technical Physics, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany.

Forschungszentrum Karlsruhe (FZK) is contributing to the ITER (Latin: The way) project, the next

generation fusion machine. ITER is the experimental step between today’s studies of plasma physics

and tomorrow's electricity-producing fusion power plants. It is an international project involving

many Associations from all over the world. The philosophy of the ITER construction, which is

planned to be ready in ten years from now, is based on in-kind contributions. This means that each

Association is actively taking responsibility for the components it provides to ITER: responsibility in

cost, time, compliance to the Technical Specification, and quality. Within the general Quality Assurance

framework which is set by the ITER Legal Entity, there is quite some flexibility left for the individual

Association as to how fulfil quality aspects for the specific component; this approach is

typical for a big R&D project, such as ITER, involving many prototypical components. Forschungszentrum

Karlsruhe is expected to become the leading Association for provision of the large

tailor-made cryopumping systems for ITER.

This talk exemplifies the FZK experiences of manufacturing and the related quality assurance management

for a recently accomplished R&D project, namely for a cryosorption pumping system used

in a test facility of a neutral beam injector that will be used to heat the plasma of a nuclear fusion reactor

with a beam of deuterium or hydrogen molecules. The huge gas throughput into the vessel of

the test facility results in challenging needs on the cryopumping system, comprising two identical

tailor-made pumps. To establish a mean pressure of several 10 -5 mbar in the test vessel a pumping

speed of about 350 m 3 /s per pump is needed. This was realized with charcoal coated cryopanels

which effectively pump hydrogen. For the cooling of the cryopanels, liquid helium at saturation

pressure is used and therefore a two-phase forced flow in the cryopump system must be controlled.

FZK received the responsibility to design, build, install and test the hardware for this task. The FZK

specified requirements, detailed in 11 individual technical specifications which each included strict

QA requirements. The manufacturing of the components were placed with a large number of industrial

companies within Europe. The central contract for the assembly of the cryopumps was placed

with an industrial company with experience in manufacture of advanced scientific components. This

Main Assembly Contractor (MAC) manufactured the cryopumps using FZK design and drawings,

but MAC also received a number of special components as FZK free issue items, where FZK was responsible

for the testing and quality control before, during and after the manufacture.

This presentation begins with a short outline of the cryopumping system design. It then identifies the

FZK activities during some of the manufacturing processes, in particular the Third Party premanufacturing

approval, construction approval, inspection of approved materials, checking welders´

qualifications, signing quality plans, witnessing the pressure testing, witnessing the vacuum leak testing,

etc. The vacuum integrity of the different circuits is of paramount importance and vacuum leak

testing has been included as holding points in the Quality Plan. All components have been tested to


JUNE 28 WEDNESDAY MORNING

WS-18-TuA-INV.10 SPANISH SYNCHROTRON RADIATION: SOURCE: PRO-

JECT STATUS AND VACUUM SYSTEM. Ll. Miralles and E. Al-Dmour. CELLS, Barcelona.

Spain

The Storage Ring ALBA is a 3 GeV third generation synchrotron light source under construction in

Barcelona (Spain). ALBA is optimized for high photon flux density with a beam emittance of 4.5

nm.rad and a large number of straight sections for Insertion Devices (3´ 8 m, 12´ 4.2 m and 2´ 2.6 m)

in a relatively small circumference of 268.8 m. Top-up operation is foreseen from the start. The injector

complex will consist of a 100 MeV Linac and a full energy Booster with a rather small emittance

9nm.rad. The design of the lattice and of the major components of the accelerator complex

(Linac and Booster, Magnets, RF system, Vacuum system) has been completed and the procurement

procedure has started for the large majority of them. The construction of the building is planned to

start in the first half of 2006 and the commissioning of the storage ring is foreseen for the end of

2008. This report gives an overview of the status of the project.

107


JUNE 28 WEDNESDAY MORNING

WS-18-WeM-INV.9 PHYSICAL AND TECHNOLOGICAL ASPECTS OF MEMS VAC-

UUM PACKAGING. F. Völklein, A. Meier, FH Wiesbaden, University of Applied Sciences. Am

Brückweg 26, D-65428 Rüsselsheim, Germany

The realization of Micro Electro Mechanical Systems (MEMS) or Micro Opto Electro Mechanical

Systems (MOEMS) requires sofisticated fabrication technologies based on thin film deposition,

photolithography and etching techniques. MEMS fabrication can be divided into three

major groups:

i) fabrication with additive and subtractive processes on the wafer level

ii) packaging, involving processes such as bonding, lead attachment and encapsulation in a protective

body or in cavities with reduced gas pressure (vacuum)

iii) testing, including package leak test, electrical integrity and MEMS functionality.

The last two process groups incorporate the most costly steps. MEMS packaging is more difficult

and expensive than packaging of Integrated Circuits (IC) and may be totally different (e.g. for gas

sensors) from IC housing.

MEMS vacuum packaging is required for accelerometers in order to optimize the damping of the devices.

High-Q micro resonators might need a good vacuum. Mechnical vacuum sensors using piezoresistive

or capacitive measuring effects include small cavities (volumes in the order of 1 mm³)

with reduced reference pressure or vacuum.

Cavity sealing can serve as a batch-compatible packaging technique by encapsulating a chip feature

or whole chip at a time. Chip features can be sealed by surface micromachining using Polysilicon or

Silicon Nitride deposition techniques and sacrificial layer technology. Such micromachined surface

packages (microshells) are much smaller than typical bulk MEMS packages. Microshells can be

made by defining thin gaps (100 nm) between the substrate and the perimeter of the structural elements

by etching away a sacrificial layer sandwiched between the two and then sealing the resulting

gaps. In so-called reactive sealing thermal oxidation of the Polysilicon and Si-substrate seals the narrow

openings left after removal of the spacer phosphosilicate (PSG) sacrificial layer. Alternatively,

sealant films, such as oxides and nitrides, can be deposited over small etchant holes. The first commercial

absolut Polysilicon pressure sensor incorporates such a reactively sealed vacuum shell. Epitaxial

cavity sealing and HEXIL cavity sealing are alternative technologies. These and other lithography-defined

packages, such as those involving ultraviolet patternable polymers, might be an integral

part of the overall fabrication processs and lend to inexpensive batch solutions.

In bulk micromachining and Si fusion-bonded (SFB) surface micromachining, cavities are fabricated

by bonding, respectively, a glass plate (anodic bonding) or a Si wafer (fusion bonding) over etched

cavities in a bottom Si wafer. Field-assisted thermal bonding (anodic bonding, also known as electrostatic

bonding) can be established between a sodium-rich glass and Silicon at relatively low process

temperatures. This method is mostly applicable to wafer-scale chip bonding. SFB is performed

between flat Si wafers with slightly oxidized surfaces. When incorporating an intermediate layer between

two substrates, many thermal vacuum bonding techniques are feasible. Silicon microstructures

can be sealed together by eutectic bonding, e.g. Au-Si eutectic bonding at 363°C. The most important

problems of MEMS vacuum packaging are the very small volumes of cavities combined with

the outgassing during the sealing process. Long term stable vacuum in microcavities can be realized

by using thin getter layers and sealing materials with low permeation coefficients.

106


WS-18 SESSION

105


JUNE 28 WEDNESDAY MORNING

JS2-WeM-OR.5 DECORATIVE COATINGS OF TITANIUM OXIDE OBTAINED BY

PVD. J.A. García, R. Martínez. M. Rico and R.J. Rodríguez. Asociación de la Industria Navarra.

C/San Cosme y San Damián s/n, Pamplona 31191 Spain.Email: jagarcia@ain.es

In the last years PVD techniques have strongly emerged in the European market of the decorative

coatings. Faucets and other bath accessories are actually been coated with ceramic films like TiN

(golden yellow) and TiCN (brass) with excellent reproducibility and corrosion resistance, but the use

of these kind of hard coatings just provide a limited list of metallic colours.

In the recent years a wider colour range are been achieved using optical interference phenomena by

depositing nanometric metal Oxide films. It is possible to obtain different colours by controlling the

final thickness of the oxide layers. This article gathers the research to obtain different interference

colours, reports the obtained reflectance curves and tries to find the relations between the oxide

thickness measures by Glow discharge optical emission spectrometry with the colour parameters

measured with a spectrophotometer. Microstructure and thickness had also been measured by using

field emission scanning electron microscopy. As conclusion we can demonstrate that the final colour

is the results of the destructive interference, depending of the relation between the wave length of the

colour and the thickness of the oxide film.

Keywords. Decorative coatings, Interference colours, GDOES, FESEM

104


JUNE 28 WEDNESDAY MORNING

JS2-WeM-OR.4 HARDNESS AND TRIBOLOGY MEASUREMENTS ON ZrN COAT-

INGS DEPOSITED BY REACTIVE SPUTTERING TECHNIQUE. M. A. Auger. Departamento

de Física. Universidad Carlos III. Avda. de la Universidad, 30. 28911 Leganés, Madrid.

Spain. J. J. Araiza. Unidad Académica de Física. Universidad Autónoma de Zacatecas. Avda. Preparatoria

Nº 301. Fracc. Progreso. Zacatecas, Zac. 98000 Méjico. C. Falcony. Departamento de Física.

CINVESTAV-IPN. Aptdo. 14-740. Méjico D.F. 07360 Méjico. O. Sánchez and J.M. Albella. Departamento

de Física e Ingeniería de Superficies. Instituto de Ciencia de Materiales de Madrid-CSIC. C/

Sor Juana Inés de la Cruz, 3. 28049 Cantoblanco, Madrid. Spain.

Thin films based on transition metal nitrides have been widely used in many applications because of

their interesting properties (mechanical, tribological, chemical stability, etc.) together with their

shiny and golden appearance, which make them highly attractive for applications as protective and

decorative coatings in different industrial and commercial sectors.

In this work, a series of ZrN coatings have been grown in a rf sputtering deposition chamber, where

different ratios of Ar/N 2 gases (5/1, 5/5, 1/5 sccm) were introduced during the process as a reactive

atmosphere. Once deposited, the coatings were thermally treated in a 500 o C oxygen atmosphere trying

to promote the oxynitride formation (ZrNO), which has been proposed as a suitable material for

being used as optical and decorative coatings. Due to the incorporation of oxygen to the matrix of

covalent metal-nitrogen bonds, the electronic properties are modified giving place to interesting

changes in the colour range of the coatings, thus allowing the control of the surface appearance in

decorative applications.

The chemical composition, mechanical and tribological properties of the as-deposited and thermally

treated samples have been measured by different techniques: EDX, nanoindentation and pin-on-disk

techniques respectively. ZrN samples grown at 5 sccm Ar + 1 sccm N 2 showed a composition close

to the stoichiometry, and offered the best mechanical and tribology behaviour. These samples, after

being subjected to the oxygen thermal treatment, improve even more their hardness, making them

more suitable for protective and decorative purposes.

103


JUNE 28 WEDNESDAY MORNING

JS2-WeM-OR.3 TRIBOLOGICAL CHARACTERIZATION OF TUNGSTEN NITRIDE

COATING AT ELEVATED TEMPERATURE. T. Polcar, N.M.G. Parreira and A. Cavaleiro a *.

ICEMS – Grupo de Materiais e Engenharia de Superfícies, Faculdade de Ciências e Tecnologia da

Universidade de Coimbra – Pólo II, 3030-201 Coimbra, Portugal. * To whom all correspondence

should be addressed (albano.cavaleiro@dem.uc.pt)

Transition metal nitrides are known for the unique combination of excellent mechanical properties

(hardness and Young’s modulus), high melting point, good chemical stability and high electrical

conductivity. However, tungsten nitrides still stand aside of the main attention, particularly compared

to titanium or chromium nitrides. The first studies of tungsten nitrides thin films were performed, basically,

for electronic applications such as, semiconductors or diffusion barriers. In the 90´s, W-N

coatings were started to be studied for mechanical applications and further studies were performed

on the addition of different elements (e.g. W-Ti-N and W-Si-N) in order to improve their mechanical

properties. There are only few studies dealing with tribological properties of tungsten nitrides and

showing their good wear resistance. In our previous study, tungsten nitride coatings with different nitrogen

content showed excellent wear resistance in case of sliding against ceramic Al 2 O 3 and Si 3 N 4

balls. However, many engineering applications require good tribological properties, particularly wear

resistance, at elevated temperature. Thus, the present study is focused on the tribological behaviour

(friction coefficient and wear rate) of tungsten nitride coating at temperature in the range 20 - 600°C.

The structure, hardness, friction and wear of tungsten nitride coating prepared by dc reactive magnetron

sputtering were investigated. The tribological tests were performed on a pin-on-disc tribometer

in terrestrial atmosphere with Al 2 O 3 balls as sliding partner. The wear tracks and the ball wear scars

were investigated by scanning electron microscopy in order to characterize the dominant wear

mechanisms. The coating wear rate was negligible up to 200°C exhibiting a decreasing tendency;

however, the wear dramatically increased at higher temperatures. The coating peeled off after the test

at 600°C.

102


JUNE 28 WEDNESDAY MORNING

JS2-WeM-INV.2 TRIBOLOGICAL CHARACTERIZATION OF METAL CAR-

BIDE/AMORPHOUS CARBON NANOCOMPOSITES: FROM MACRO TO THE MICRO-

SCALE. J.C. Sánchez-López*, D. Martínez-Martínez, C. López-Cartes, A. Fernández. Instituto de

Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, Avda. Américo Vespucio 49, 41092-

Sevilla, Spain. *E-mail: jcslopez@icmse.csic.es

The design of multilayered and nanocomposite coatings structures have allowed to achieve superior

hardness, toughness and excellent wear resistance useful for many industrial applications. The optimization

of the tribological performance of such materials represents a challenge as depends not only

on factors intrinsic to the coatings (chemical composition, microstructure, phase composition, texture…)

but, besides, others related to the application conditions (adhesion to the substrate, nature of

the counterfaces, environment, load, etc.). In this work, we review the results obtained for nanocomposite

coatings made of nanocrystalline metal carbides and amorphous carbon (a-C) prepared by

PVD techniques. Their characterization appears complicated mainly due to the lack of long-range

order and the heterogeneity in chemical compositions at the nanometric scale. The nanocrystalline/amorphous

ratio appears to be a key-parameter to control the tribological properties and its

quantification results always not easy. Focusing mainly in the TiC/a-C system prepared by magnetron

sputtering as example, it is showed how the investigation of chemical and structural features at

the micro-scale help to determine the aspects influencing the tribological performance at the macroscale.

By varying the power applied to each target (titanium or graphite), it was possible to prepare a

wide family of film structures covering from a quasi-polycrystalline TiC to a nanocomposite formed

by nanocrystals of TiC. The microstructure of one coating, shown in Fig. 1, reveals a nanometric

grain boundary network around TiC crystals of 5 to 10 nm. A complete characterization has been accomplished

by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy

(TEM), electron diffraction and electron energy-loss spectroscopy (EELS) and X-ray photoelectron

spectroscopy (XPS), pin-on-disk and nanoindentation measurements. EELS and XPS

techniques are demonstrated to be very appropriate tools for the estimation of the amorphous phase

inside the nanocomposite because they are sensitive to the bonding environment. In the Fig. 2 it is

depicted the modification of the shape and position of the C K-edge for different coatings when the

contents of TiC and a-C are varied. The increment of the TiC contribution is accompanied by a gradual

rise of the friction coefficient due to the lack of sufficient amorphous lubricant phase. Combining

the complementary information given by the different techniques it was possible to obtain a mapping

of the tribological and mechanical properties as a function of the synthesis conditions that helps in

the selection of the best coating for specific applications.

Fig. 2 C K-edge

EELS spectra and

associated friction

values for different

TiC/a-C coatings

Fig. 1: HRTEM image for a TiC/a-C film

101


JUNE 28 WEDNESDAY MORNING

JS2-WeM-OR.2 WEAR RESISTANCE OF TITANIUM-ALUMI-NIUM-CHRO-

MIUM-NITRIDE NANOCOMPOSITE THIN FILMS. A. Alberdi, M. Marín, B. Díaz.

Fundación Tekniker. Avda. Otaola, 20. 20600 Eibar (Spain). O. Sánchez. Institute of Materials

Science (ICMM). Cantoblanco, 28049 Madrid (Spain)

Titanium nitride, titanium-aluminium nitride and chromium nitride are now used widely in

manufacturing industry to protect cutting and forming tools against wear. TiN was the first

PVD ceramic coating to be used successfully to machine steel in industry and it is still the most

recognized. TiN is a wear resistant coating suitable for a wide range of applications. It is used

for machining carbon stainless steels, cast irons and aluminium alloys, protecting dies, moulds

and a range of metal stamping and forming tools. However, TiN has now been superseded in

many applications by TiAlN, which offers superior performance for a range of metal machining

and fabrication applications. It has been pointed out that the reason for this better performance

is the formation of aluminium oxide on the surface, which increases its operational temperature

range. Although CrN is softer than TiN, CrN is a tough ceramic coating with good

oxidation resistance. Presently, CrN is the PVD hard coating recommended for most metal

forming applications.

Advanced PVD coatings based on TiAlN are being developed recently, which possess enhanced

high temperature oxidation and wear resistance. Typical strategy to enlarge the temperature

range of TiAlN is the addition of metals able to generate high resistant oxides, like

chromium, molybdenum, yttrium or vanadium.

In this way, authors have developed novel TiAlCrN multilayered nanocomposite thin films,

which alternate CrN and TiAlN individual 10-12 nm thickness layers up to a total thickness of

1-3 μm. These coatings were grown on WC-Co inserts and high speed steel samples by simultaneous

arc evaporation of pure Cr and Ti-Al alloy targets. Wear resistance of these coatings

was studied through high temperature pin-on-disk experiments. Results demonstrated that this

kind of coating structures improved several times the wear resistance at high temperature of

commercially available TiAlN coatings.

Key words: TiAlCrN ceramic coatings, physical vapour deposition, high temperature wear resistance.

100


JUNE 28 WEDNESDAY MORNING

JS2-WeM-OR.1 TRIBOLOGICAL PROPERTIES OF SILICON NITRIDE CERAMICS

COATED WITH DLC AND DLC-Si AGAINST 316L STAINLESS STEEL J. R. Gomes. Departamento

de Engenharia Mecânica, CIICS, Universidade do Minho, 4800-058 Guimarães, Portugal.

J. M. Carrapichano. Departamento de Engenharia Mecânica, Instituto Superior de Engenharia de

Coimbra, 3040-228 Coimbra, Portugal. S. S. Camargo Jr., R. A. Simão, C. A. Achete. Departamento

de Engenharia Metalúrgica e de Materiais, Universidade Federal do Rio de Janeiro, Cx. Postal

68505, 21945-970 Rio de Janeiro, RJ, Brazil. R. F. Silva. Departamento de Engenharia Cerâmica e

do Vidro, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal.

Diamond-like carbon (DLC) is an adequate coating on a large variety of materials for tribological

purposes. Its intrinsic hardness, smoothness and solid lubricious capability are key properties that afford

an outstanding combination of low friction coefficient and high wear resistance. However, the

performance of a tribosystem is also determined by the type of counterface material, the environmental

conditions and the presence or not of interfacial media. For example, in the automotive parts

industry, the valve guides or the transmission gears are today coated with DLC. Another practical

example of contacts that may involve steel as the mating material of DLC are forming tools to manufacture

steel products. Plasma enhanced chemical vapour deposition (PECVD) of DLC-Si or pure

DLC coatings were performed, respectively, by conventional rf glow discharge from gaseous mixtures

of methane and silane or taking only pure methane. In this work, an engineering ceramic, silicon

nitride (Si 3 N 4 ), is used as DLC substrate aiming the minimization of adhesion problems, usually

found when some metallic substrates are employed. The ceramic substrates were placed onto the

cathode of the deposition system where the rf power was applied achieving self-bias voltages varying

from -200 to -800 V.

The tribological properties were assessed by pin (316L stainless steel)-on-disc (Si 3 N 4 ) experiments,

without lubricant, at room temperature, under ambient air and 50-60% relative humidity. The normal

applied load assumed the values of 10 N and 20 N. The sliding speeds varied from 0.2 m/s to 1.0

m/s. The characterisation of the disc and pin worn surfaces was carried out by scanning electron microscopy

provided with energy dispersive X-ray spectrometry (SEM/EDS) and atomic force microscopy

(AFM). A first set of experiments was carried out in order to compare the tribological behaviour

of DLC-Si and pure DLC coatings on Si 3 N 4 . An early partial delamination of the DLC-Si coatings

was observed, although leading to a steady-state friction regime with friction coefficients

around 0.14, a low value in unlubricated conditions. This favourable frictional response is due to the

wear-induced surface graphitisation and to the role of self-lubricating layers of adhered debris in

both the sliding surfaces. The stainless steel contact surface was extensively covered by a Si, C and

O rich tribolayer, promoting a third-body protection to the steel pin. An improved tribological response

was obtained with pure DLC coated Si 3 N 4 discs sliding against the stainless steel pins. This

system almost instantaneously attains the steady-state friction regime, keeping the DLC film integrity,

contrarily to the DLC-Si damaging, which leads to noisy friction curves coming from cyclic

frictional events. The preservation of the coating demonstrates an adequate adhesion for tribological

purposes up to 20 N of applied load. The wear coefficient of the pure DLC coated Si 3 N 4 disc was, at

least, one order of magnitude lower than that of the DLC-Si coated one, always below 10 -6 mm 3 N -

1 m -1 . The set of tribological experiments of pure DLC coatings obtained under distinct self-bias application

during the PECVD process revealed that the wear coefficient values obtained for the –200V

biased coating are slightly better than those presented by the –800V biased one. However, with respect

to the friction coefficient values, a trend to lower values occurs for the –800V biased films.

Additionally, the typical friction pattern for low biased grown coating is much more unstable than

the very smooth one of the –800V biased film.

99


JUNE 28 WEDNESDAY MORNING

JS2-WeM-INV.1 SURFACE ANALYSIS OF NITRIDES AND OXYNITRIDE COM-

POUNDS WITH ION BEAMS. E. Alves, N. P. Barradas, Instituto Tecnológico Nuclear, EN. 10,

2686-953 Sacavém .F. Vaz, L. Rebouta, C. Tavares, Universidade do Minho, Departamento de

Física, 4800-058 Guimarães, Portugal. U. Kreissig, Forschungszentrum Rossendorf e.V., Postfach

510119, 01314 Dresden, Germany.

Titanium nitride and oxynitride compounds exhibit interesting properties for applications in fields

ranging from protective/decorative coatings to solar panels. The properties of these compounds are

related to the oxide/nitride ratio and can be tailored by tuning this ratio. Then, accurate composition

measurements are fundamental to understand the behaviour of these structures. Ion beam based techniques

(IBA) are unique for this purpose. The composition throughout the entire thickness of the

films was determined by Rutherford Backscatering Spectrometry (RBS). To get information on the

profile of light elements (O, N) and detect the presence of hydrogen on the films, heavy ion elastic

recoil detection analysis (HI-ERDA) was performed.

The results indicate a nearly constant stoichiometry through the entire analysed depth. The oxygen

fraction in the films increases with gas flow, reaching a value of x~0.33 for a reactive gas flow mixture

of 6.25 sccm The colouration varied from the shiny golden for low oxygen contents (characteristic

of TiN films) to dark blue for higher oxygen contents. During growth mixed zirconium nitride

and oxide phases form. Furthermore, the deposition rate correlates with the oxygen content variations,

showing a continuous decrease with reactive gas flow.

98


JS2 SESSION

97


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WEM-OR.8 THE TRIBOLOGICAL BEHAVIOUR OF W-S-C FILMS IN PIN-

ON-DISK TESTING AT ELEVATED TEMPERATURE. M. Evaristo, T. Polcar, A. Cavaleiro,

ICEMS -Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Dep. Eng. Mecânica, Rua

Luís Reis Santos, 3030-788 Coimbra, Portugal

Transition metal dichalcogenides (TMD) are well known for their self lubricant properties, due to

unique crystal structure. However, the structure of TMD presents some drawbacks, particularly, they

have low hardness making them inappropriate to applications requiring high load bearing capacity.

Moreover, TMD films exhibit morphologies with high porosity promoting oxidation, particularly in

humid atmosphere or elevated temperature.

Several approaches have been used to increase the mechanical properties of TMD thin films. One of

the most successful is either doping TMD with a metal, which increases hardness, or the deposition

of an interlayer improving adhesion. MoS 2 is one of the most studied TMD, showing good results

when deposited with an interlayer and doped with Ti, Cr, and other metals.

There is a reference in literature showing that WS 2 has higher oxidation resistance than MoS 2 (about

100ºC), therefore, it is a good candidate for films with good tribological behaviour at high temperatures.

Previous works showed that the hardness and adhesion of W-S films doped with C or N deposited

with a Ti interlayer significantly increased compared to pure WS 2 . The analysis of friction and

wear behaviour at elevated temperatures was the main aim of this study.

W-S-C films were deposited by magnetron sputtering in an Ar atmosphere with a Ti interlayer. A

carbon target with several pellets of WS 2 incrusted in the zone of the preferential erosion was used.

The number of pellets was changed to modify the carbon content in the films, which varied from 26

up to 70at.%. Doping W-S films with carbon lead to a substantial increase of the hardness in the

range 4 to 10GPa; the maximum of hardness was obtained for coatings with the carbon content of

40at.%.

The XRD diffraction patterns showed that there was a loss of crystallinity with the increase of the

carbon content in the film. SEM images of the cross section of the films showed decrease of the dimensions

of the columnar structure and decrease of the porosity as the carbon content in the films increased.

The coatings were tested by pin-on-disk from room temperature (RT) up to 400ºC. At RT, the friction

coefficient was in range 0.3-0.1, and the wear rate decreased with the carbon content. At temperatures

higher than 100ºC, the friction is below 0.1 for all compositions, which can be explained

by the atmosphere drying.

The tribological behaviour of the coatings with increasing temperatures depends on the films carbon

content. For low carbon content up to 40at.%, the wear rate was almost independent of the temperature

up to 300º, while it increased dramatically in case of coatings with high carbon content. The

highest carbon content (∼70at.%) coatings were peeled off from the substrate at temperatures exceeding

100 ºC. In general, the limiting temperature for W-S-C coatings is 400ºC.

96


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WEM-OR.7 AB INITIO CALCULATIONS FOR THE EXCITED STATE AND

THE CATION OF DIPHENYL ETHER AND COMPARISON WITH REMPI EXPERI-

MENTS. M. Guerra and A. C. S. Paiva. CEFITEC Department of Physics, Faculdade de Ciências

e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.

The structure and minimum energy conformations of diphenyl ether (Ph 2 O) both for the ground state

and the first excited state are calculated using HF/6-311++G**, MP2/6-311++G**, BLYP/6-

311++G** and B3LYP/6-311++G** ab initio and density functional computations. Potential energy

surfaces are also obtained for the rotation of the phenyl rings relatively to the C-O-C plane both for

the neutral molecule and the positive ion. The global minimum of the Ph 2 O potential energy surface

was found to be a “twisted” conformation and it doesn’t change with the excitation to the first excited

state nor with a single ionization, altough the C-O-C-C dihedral angle varies slightly and the

molecule floppyness decreases. An initial study of the molecule fragmentation was performed at

B3LYP/6-311++G** theory level.

The spectra of Ph 2 O cooled in a supersonic jet expansion, obtained with one-color resonance enhanced

two-photon ionization suggests the existence of different conformations [1] . The first excited

state low-frequency vibrations for three of the conformers were investigated using a Configuration

Interaction aproach (CI-Singles) and Complete Active Space Multiconfiguration Self Consistent

Field (CASSCF) method. The comparison between the calculated and observed spectra for all the

conformers thus allows us to assign the major bands.

Keywords: Conformational analysis; Diphenyl ether; Photoionization; Ab initio calculation

[1] A. C. S. Paiva et al., International Journal of Mass Spectrometry 221 (2002) 107-115

95


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-OR.6 SURFACE ANALYSIS OF NBR ELASTOMERS MODIFIED

WITH DIFFERENT PLASMA TREATMENTS. L. Martínez, L. Álvarez, Y. Huttel, J. Méndez,

E. Román. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC) Cantoblanco, 28049-Madrid,

Spain. A. Vanhulsel, B. Verheyde, R. Jacobs, Flemish Institute for Technological Research (VITO).

Boeretang 200, 2400-MOL, Belgium.

In this work, three rubber–like materials with applications applied in the automotive industry were

studied: two Nitrile Butyl Rubber (NBR 7201 and NBR 9003) and one Hydrogenated Nitrile Butyl

Rubber (HNBR 8001). Different atmospheric pressure plasma treatments were used to modify the

surface properties of these materials in order to improve their tribological (properties). Surface

analysis of the samples by means of X-ray Photoelectron Spectroscopy (XPS) was performed in order

to get information about the surface chemistry and the elemental composition of the contact surfaces.

In addition, wetting experiments were also performed by measuring the contact angle with in

the frame of the sessile drop method. The obtained results allow an evaluation of the surface free energy

of the solids and of the impact of different plasma treatments. The XPS results showed a modification

of the surface composition of both NBR rubbers, while the same treatments produced slight

modifications on the surface chemistry of the HNBR. The main modification was based on an increase

in the oxygen content. The combination of N 2 and CH 3 COOH produced the strongest modifications

of the surface composition of the tested elastomers. All these surface modifications also produced

a change on the surface energy of the rubber-like materials. The results obtained in the contact

angle measurements revealed that the plasma treatments produced a modification of the wettability

of the rubber-like NBRs and, therefore, a modification of their surface free energy.

94


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-OR.5 DEVELOPMENT OF AN APPLICATION FOR MONI-

TORIZATION AND ANALYSIS OF THE ELECTRIC SIGNAL OF AN ULTRAVIOLET

PHOTOELECTRON SPECTROMETER. P. M. S. Cristo, A. A. Dias, P. Vieira, M. L. Costa.

1 Centre for Physics and Technological Research, CEFITEC, 2 Departamento Física, Faculdade de

Ciências e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, 2829-516, Caparica, Portugal.

e-mail: aad@fct.unl.pt

The development of an application for monitorization and analysis of the electric signal of an ultraviolet

photoelectron spectrometer [i], witch allows for more precision in both the spectrometer

analysis parameters and in the collected data, is presented.

The principal features are the control of the voltage applied to the analyser hemispheres and the acquisition

of counts from the spectrometer.

A Labview programming environment was chosen, jointly with a Data Acquisition board for the

counting, input and output data.

The construction of a Digital-Analogic converter is also included in the project in order to convert

the digital signal available in the acquisition board and controlled by the Labview to analogical data

for input in the spectrometer.

References

[i] F. Innocenti, L. Zuin, M.L. Costa, A.A. Dias, A. Morris, A.C.S. Paiva, S. Stranges, J.B. West,

J.M. Dyke, J. Elec. Spec. Rel. Phen. 2005, 142, 241-252.

93


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-OR.4 DESIGN OF AN ELECTROSTATIC LENS SYSTEM FOR AN

ULTRAVIOLET PHOTOELECTRON SPECTROMETER. R. M. Pinto 1,2 , A. A. Dias 1,2 and

M. L. Costa 1,2 . 1 Centre for Physics and Technological Research, CEFITEC, 2 Departamento Física,

Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, 2829-516,

Caparica, Portugal e-mail: aad@fct.unl.pt

The control of an electron beam plays an important role in most of the electron spectrometer systems,

nowadays. Although the use of electrostatic lenses, for purposes of focusing the particles, is

not always necessary, the overall quality of the system in which they are inserted can be improved.

This work aims to design an electrostatic lens system [i] that improves the resolution at the entrance

of a hemispherical deflection analyzer, of a working ultraviolet photoelectron spectrometer [ii,iii],

while maintaining a constant transmission.

The spectrometer does not have any kind of controlled focusing device other than a spatial collimator.

An optimal solution has to be found, concerning the dimensions of the existing apparatus. Simulations

using ion optics programs and the study of several lenses configurations are the suitable

means to reach such a goal. The existence of aberrations is taken into account.

References

[i] O. Sise, M. Ulu, M. Dogan. Nucl. Instr. and Meth. in Phys. Res. A 2005, 554, 114-131.

[ii] J.M. Dyke, G. Levita, A. Morris, J.S. Ogden, A.A. Dias, M. Algarra, J.P. Santos, M.L. Costa,

P. Rodrigues, M. Andrade, M.T. Barros. Chem. Eur. J. 2005, 11, 1665-1676.

[iii] L. Beeching, A.A. Dias, J.M. Dyke, A. Morris, S. Stranges, J. West, N. Zema, L. Zuin, Molecular

Physics 2003, 101, 575-582.

92


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-OR.3 WORK FUNCTION CHANGES INDUCED BY TEMPERATURE

IN Ag/TiO 2 SURFACES. H. P. Marques, A. R. Canário, A. M. C. Moutinho and O. M. N. D.

Teodoro CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade

Nova de Lisboa, 2829-516 CAPARICA, Portugal

When one studies the catalytic behaviour of a surface, the energy required to remove electrons from

the surface is a meaningful parameter since electron transfer is involved in many surface reactions.

Therefore, the surface work function is important to understand the mechanisms of heterogeneous

catalysis.

Growth dynamics of silver clusters supported on TiO 2 (110) mono-crystals have been studied by

several authors [1-5]. Silver atoms deposited in the crystal at room temperature exhibit a 3D Volmer-

Weber growth mode. When the substrate is cooled to LN 2 temperature, the Ag atoms have very low

surface mobility and a quasi-2D growth is observed [2].

The work function measurements performed during cluster growth show different behaviour depending

on the substrate temperature, which translates on the cluster size [6]. During growth, at lower

temperature the WF changes more rapidly and tends to a lower value than at room temperature.

In this work we studied the work function as a function of the substrate temperature. One equivalent

monolayer of silver was deposited on a TiO 2 (110) surface at LN 2 temperature and a base value for

the work function was determined. The substrate was then annealed for 5 minutes. The sample was

allowed to cool down again to LN 2 temperature and the work function was measured. The procedure

was repeated for increasing annealing temperatures up to 200ºC.

For all work function measurements the onset method was used. The secondary electron threshold is

shifted in energy according to the work function change.

Keywords: Work function, titanium oxide, silver clusters.

[1] U. Diebold, Surface Science Reports, 48 (2003) 53.

[2] C.T. Campbell, Surf. Sc. Reports, 27(1997) 1 111

[3] C. Su, J.C. Yeh, J.L. Lin and J.-C. Lin, App. Surf. Sci. 169 (2001) 366.

[4] K. Luo, T.P. St Clair, X. Lai, and D.W. Goodman, J. of Phys. Chem. B 104 (2000) 3050.

[5] A.R. Canário, E.A. Sanchez, Yu. Bandurin and V.A. Esaulov, Surf. Sci. 547 (2003) L887

[6] H.P. Marques, A.R. Canário, O.M.N.D. Teodoro and A.M.C. Moutinho Riva V

proceedings, submitted to Vacuum

91


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-OR.2 PLANAR MAGNETRON DISCHARGE. AN EXPERIMENTAL

PROFILE ANALYSIS OF THE TARGET EROSION BASED ON A TWO-DIMENSIONAL

FLUID MODEL IN THE STEADY STATE. M. L. Escrivão, P. J. S. Pereira*, M. R.

Teixeira and M. J. P. Maneira. CeFITec, Departa-mento de Física, Faculdade de Ciências e Tecnologia

da Universidade Nova de Lisboa, Quin-ta da Torre, 2829-516, Caparica, Portugal. * Also in

Área Científica da Matemática, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro

Emídio Navarro, 1949-014 Lisboa, Portugal

.

In the present work the erosion depth is measured along a diameter of a circular magnetron target.

The horizontal and vertical components of the magnetic induction are measured at points of the

plasma that are vertically above this diameter and at different distances from the target.

The experimental profile of the target erosion is analysed on the basis of the plasma density distribution

near the target which is obtained using a two-dimensional fluid model in the steady state.

90


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-OR.1 USE OF A RADIO-FREQUENCY POWER SUPPLY COUPLED

TO A HIGH TEMPERATURE FURNACE IN ULTRAVIOLET PHOTOELECTRON SPEC-

TROSCOPY. E. M. C. C. Reis 1,2 , A. A. Dias 1,2 , O. M. N. D. Teodoro 1,2 and M. L. Costa 1,2 . 1 Centre

for Physics and Technological Research, CEFITEC. 2 Departamento Física Faculdade de Ciências e

Tecnologia, Universidade Nova de Lisboa, Monte de Caparica, 2829-516, Caparica, Portugal. e-

mail: aad@fct.unl.pt

Temperatures up to 2500 ºC have to be attained for analysing solid samples by Ultraviolet Photoelectron

Spectroscopy (UVPES), using a high temperature furnace[i]. A radio-frequency (RF) power

supply seems ideal for this purpose [ii].

The RF source, operating near the photoelectron spectrometer, creates an electromagnetic field that

causes interference in photoelectron trajectories. In order to eliminate this effect the RF power supply

should be used in a pulsed mode in conjunction with a linear gate in detector circuits.

The frequency chosen to obtain these pulses is of 50 Hz, since that is the frequency used by the

mains. The 50 Hz waves are rectified, being allowed to pass only the positive voltages, eliminating

the negative ones.

Considering that the maximum power available from the generator is reduced to less than half of its

original value, as a result of the pulses, a considerable amount of power is necessary to raise the

temperature.

Modifications performed in both a RF power supply and detector circuits, together with its coupling

to an existing high temperature furnace will be presented.

References

[i] J.M. Dyke, G. Levita, A. Morris, J. S. Ogden, A.A. Dias, M. Algarra, J.P. Santos, M.L. Costa,

M.T. Barros, J. Phys. Chem. A 2004, 108, 5299-5307.

[ii] D. Bulgin, J. Dyke, F. Goodfellow, N. Jonathan, E. Lee, A. Morris, J. Elec. Spec. Rel. Phen.

1977, 12, 67-76.


89


JUNE 28 WEDNESDAY MORNING

RIVA-SS-WeM-INV.1 STM STUDY OF MODIFICATIONS ON VACUUM FIRED 304L

STAINLESS STEEL SURFACES. M. Leisch and A. Stupnik. Institute for Solid State Physics,

Graz University of Technology, Petersgasse 16, 8010 Graz, Austria

In UHV and XHV applications high temperature bakeout (vacuum firing) is a common method to reduce

the hydrogen outgassing rate from stainless steel surfaces. This procedure reduces the amount

of hydrogen in the bulk. At low bulk concentration hydrogen, outgassing is basically limited by surface

recombination.

The surface of glass bead blasted 304L steel samples was investigated by STM after normal bakeout

procedure at 300°C and after vacuum firing at 1000°C. During vacuum firing a complete reconstruction

of the surface can be observed. Already after 5 min of vacuum firing the formation of (111) terraces

with monoatomic steps can be found. Slightly tilted crystallites exhibit (111) terraces intersected

by bunched steps and facets. These facets form a nearly regularly pattern corresponding in

orientation almost to the (100) and (110) planes. After 15 min vacuum firing large (111) terraces

with extensions up to 200nm intersected by bunched steps can be observed. The general appearance

of the surface after vacuum firing indicates a significant reduction of active sites for recombination

of hydrogen. This supports the present understanding of outgassing for this material.

Supported by „Zukunftsfonds des Landes Steiermark“

88


RIVA-SS SESSION

87


JUNE 28 WEDNESDAY MORNING

WeM-Pl.3 FUNCTIONAL CERAMIC THIN FILMS, NEW MATERIALS FOR THE

FUTURE, FROM NATURALLY NANOLAMINATED MAX-PHASES TO TAILORED

NANOCOMPOSITES OF CARBIDES, OXIDES AND NITRIDES. H. Högberg, Thin Film

Physics Division, Department of Physics (IFM), Linköping University, SE-58183 Linköping, Sweden.

There is a strong desire to design a material with properties that match the demands foreseen in future

applications. Thus, the development of functional materials is gaining increased attention in materials

science today. This presentation focuses on two such highly promising branches of functional

thin films, namely the layered ternary ceramic compounds known as the M n+1 AX n (n=1-3) phases,

where M is an early transition metal (Ti, Nb), A is a group 13-15 element (Al, Si, Ge), and (X) is either

C or N, and nanocomposites from the TiC/SiC, TiN/SiN x and ZrO 2 /Al 2 O 3 systems. A limited

miscibility for one of the constituents is inherent to all of these systems, which causes segregation of

the element during synthesis. For the MAX phases, typically synthesized as bulk materials at temperatures

of ∼1300 o C, the process yields an anisotropic crystal structure in which MX blocks are interleaved

by pure A-element layers. This nanolaminated structure give rise to the unique set of properties

for these materials as reported by Barsoum et al. Typically the MAX phases show high oxidation

resistance in combination with good thermal and electrical conductivities. These attributes are

also ideal for advanced thin film applications were multi-functionality is required at elevated temperatures

and/or harsh environment. Recently, we have developed dc magnetron sputtering processes

for the growth of MAX-phase thin films from the systems Ti-A-C, A=Al, Si, Ge, or Sn, using either

growth from elemental sources or Ti 3 SiC 2 and Ti 2 AlC (MAXTHAL®) targets. The processes enables

the growth of epitaxial thin films on Al 2 O 3 (0001) substrates at substrate temperatures in the region

700-1000 o C, including known bulk phases such as Ti 2 GeC, Ti 2 SnC, Ti 3 SiC 2 , and Ti 3 GeC 2 as

well as new phases Ti 4 SiC 3 , Ti 4 GeC 3 , and Ti 3 SnC 2 . Characterization with four-point probe resistivity

measurements shows that our thin films are good conductors. Nanoindentation confirms the ductile

deformation behavior of the MAX phases and reveals details on the formation of pile up.

For the nanocomposite thin films from particularly the TiN/SiN x system the pioneering work by

Vepřek et al has provided invaluable knowledge regarding the microstructure design of films with

improved properties. Their studies show that increased hardness is only achieved when the secondary

amorphous phase (SiN x ) form a 1-2 monolayer thick tissue around small (


PLENARY

85


WEDNESDAY

84


JUNE 27 TUESDAY AFTERNOON

WS-18-TuA-INV.8 ADVANCED PROCESS AND EQUIPMENT CONTROL (APC/AEC)

THROUGH FINE GAS ANALYSIS IN VACUUM SYSTEMS FOR SEMICONDUCTOR

MANUFACTURING. Giuseppe FAZIO, ST Microelectronics - Italy

In the Advanced Process and Equipment Control (APC/AEC) the studies and the evaluations related

to new methodologies and new devices are considered key activities.

In vacuum chamber the Optical Emission Spectroscopy (OES) and Residual Gas Analyzer (RGA)

are two instruments consolidated and widely utilized due to their high performance and flexibility.

OES

RGA

OES and RGA applications

Main application

Other application

Process Control

Equipment Control

(i.e., End Point Detection) (i.e., finger print equipment)

Equipment Control

Process Control

(i.e., leak detection)

(i.e., degas step optimization)

Also from APC/AEC point of view these two instruments (OES and RGA) and their various applicable

methodologies (process and equipment control) have to be continuously developed.

Some of our direct experiences concerning these aspects will be showed.

OES example

Optical emission spectroscopy (OES) is widely used to perform in situ characterization and plasma

processing control, as for instance in dry etching end point detection.

In current practice only UV-VIS range is used, which corresponds to electronic transitions of molecular

or atomic levels.

However, when areas to be patterned within the wafer are small, and etching selectivity is not well

known, the OES could not be enough.

To detect the optical end point a new portion of the spectra has been studied (corresponding to molecular

vibrational modes) and its emission enhancement.

RGA example

When the pressure is lower than 10mTorr a miniature array of quadrupole mass spectrometers has

been considered (Micropole sensor).

This sensor has a small size and it is feasible to install it in a small volume, without loosing high performances,

and turns out to be very flexible on applications.

Recently an instrument for advanced diagnostic using the RGA Micropole has been developed.

This instrument allows technicians to control the vacuum chambers in order to have higher accuracy

and faster analysis, requirements more and more important for hi-tech industries like the semiconductor

one.

When the pressure is higher than 10mTorr the traditional RGA (quadrupole) requires pump system.

For this reason the system is not suitable for industrial field: cumbersome and complicated from a

maintenance point of view.

Therefore, we have evaluated alternative instruments: ICP plasma source, analysis by OES of atomic

and molecular emission due to plasma excitation of residual gases.

Hardware malfunctions were simulated on etch equipment and the consequent behaviour of the

plasma emission spectrum was analyzed in order to evaluate and quantify detectable differences.

The installation of this type of sensor on Transfer Module of the metal etch tool has been planned for

the detection in line for leakage and humidity. In particular the focus concerns the wet cleaning recovery

after PM and the reduction of the possible particle contamination produced by humidity.

83


JUNE 27 TUESDAY AFTERNOON

WS-18-TuA-INV.7 THE DESIGN AND OPERATION OF THE JET VAC-

UUM AND FUELLING SYSTEMS AND THEIR RELEVANCE TO ITER. R J

H Pearce, Euratom-UKAEA Association, Culham Science Centre, Oxon, OX14 3DB.

UK . M. Wykes, ITER IT, IPP, Boltzmannstr. 2, 85748 Garching, Germany.

JET is the world largest magnetic confinement fusion device and the only device with the capability

to operate with tritium. JET first operated in 1983 and since this time it has been regularly enhanced

and upgraded. Agreement is now well advanced for building ITER at Caderache in France. JET has

played a key role in the ITER design, in particular by operating in deuterium/tritium, by testing divertor

designs, in developing first wall technology, by operating with high power heating systems

and in consolidating ITER operating scenarios.

The JET main vacuum vessel is of doubled walled construction of volume ~200m 3 and is capable of

being baked to 320 o C. It is pumped by turbo-molecular pumps in addition to a high pumping speed

cryogenic pump in the divertor region. Typically JET now operates at 200 o C with a base pressure in

the 10 -8 mbar region. The total pressure is dominated by deuterium outgassing and by the vapour

pressure of deuterium held on the supper critical helium cryogenic pumps. Impurity partial pressures

are in the 10 -10 mbar region.

The JET vacuum vessel and other vacuum containment system also act as the primary containment

system for tritium injected or stored in the JET. This necessitates the need for high integrity on all

boundary components and double containment on delicate components.

The vacuum characteristic of JET are significantly affected by plasma facing components. These

have been an important area of development and change in magnetic confinement fusion devices. On

JET the vacuum vessel’s first wall has been regularly changed, progressing from inconel, to graphite,

to the current carbon fibre composite (CFC). In addition various experiments with partial beryllium

coverage have been performed. A full beryllium wall with a tungsten coated, CFC divertor is

planned for the future as a reference for ITER.

The physics programme on JET has lead to demanding requirements for the supply of gas to the torus.

In particular the pumped divertor necessitates scenarios with high fuelling rates. In total 12 fuelling

points are used. It is required to deal with large numbers of gas species, expensive gas species,

reactive gas species as well as tritium gas. An automated system is used for introducing gas into JET.

The system gives the flexibility for gases to be changed frequently without compromising gas purity.

Three successful experimental tritium campaigns have been performed on JET. An initial tritium inventory

of 20g has been used for a total injection, to date, of ~36g. The experiments have provided

very valuable experience in complex systems on, tritium handling, retention and accounting. New

challenges will however be encountered within the ITER fuel cycle with ~3Kg of tritium proposed to

be on site and ~850Kg to be injected through the life of ITER.

The design and operation main JET vacuum and fuelling systems are described. These are compared

with the proposed systems for ITER. Where there is particular ITER relevant experience, in the design,

manufacturing, and operation of vacuum and fuelling systems, this is highlighted.

82


JUNE 27 TUESDAY AFTERNOON

WS-18-TuA-INV.6 QUALITY CONTROL AND LEAK DETECTION IN LARGE VAC-

UUM SYSTEMS. P. Chiggiato. CERN, European Organization for Nuclear Research. CH-1211

Geneva 23, Switzerland.

Large ultra-high vacuum systems can be jeopardized by the failure of a single vacuum component.

As a consequence, a careful choice of materials, assembling techniques and surface treatments is

mandatory in order to avoid leaks (both real and virtual) and excessive outgassing that could spoil

the efficiency of the pumping system. However, even if the suitable choice of the production procedure

is taken, a dedicated quality control plan is essential to avoid the result of clumsy operations

and drifts in the production parameters.

For the Large Hadron Collider (LHC), which is under construction at CERN and expected to run at

the end of 2007, thousands of vacuum components are being produced and different quality control

programs are applied. For the particular case of the about 1200 long straight section (LSS) vacuum

chambers, the quality insurance program will be reviewed by taking into account the most critical

steps of the production procedure, namely extrusion of the OFS tubes, vacuum brazing of the

flanges, TIG welding, chemical treatment of the inner surface, and deposition of the Ti-Zr-V nonevaporable

getter (NEG) thin film. Several characterization techniques are involved, for example X-

ray radiography, optical and metallurgical analysis, leak detection, surface sensitive inspection (XPS

and AES) and non-traditional vacuum measurements.

The quality control plan continues also after the installation of the components in the accelerator ring

or into complex devices like superconducting magnets and distributing field boxes. In this context,

the validation criteria for the NEG film activation process in the LSS will be presented. In addition,

an alternative method for detecting leaks in the complex cryogenic lines of the superconductive

quadrupoles of the LHC will be described.

In order to save and to simply retrieve the massive quantity of data coming from the different controls,

a dedicated software has bee developed at CERN; for most of the components installed in the

main ring, it allows the tracking of all the production and control reports together with the actual position

in the accelerator.

81


WS-18 SESSION

80


JUNE 27 TUESDAY AFTERNOON

JS1 SESSION

ROUND TABLE

CHAIRMAN: J. M. ALBELLA ICMM-CSIC-ES

PRESENTERS:

A. CAVALEIRO UNIVERSITY OF COIMBRA. PT

J.A. GARCÍA AIN, ES

F, ORGAZ MEC.ES

79


JUNE 27 TUESDAY AFTERNOON

JS1-TuM-INV.12 MICROFABRICATION BY DIRECT WRITING ON DIELECTRICS

USING ULTRASHORT LASER PULSES. J. Solis, Instituto de Optica, CSIC, Serrano 121, E-

28006 Madrid, SPAIN

Subsurface modification of transparent materials with femtosecond laser pulses is a promising tool

for the fabrication of 3-D photonic elements. However, in spite of its successful application to the

production of waveguides and other photonic elements such as gratings, waveguide amplifiers, or

photonic band-gap structures in a variety of dielectric materials, its widespread use is still hampered

by several problems related to the control of energy deposition inside the dielectric material. The

presence of spherical aberrations, as a consequence of the refractive index mismatch at the airdielectric

interface, as well as non-linear propagation phenomena have already been identified as

critical issues, very particularly in high refractive index materials. The presentation will provide an

overview of the fundamentals of this processing technique as well as different strategies aimed either

at better controlling the energy deposition inside the material or at producing functional photonic

elements in “difficult” materials like heavy metal oxide glasses.

78


JUNE 27 TUESDAY AFTERNOON

JS1-TuA-INV.11 SURFACE FUNCTIONALIZATION OF CERAMIC TILES BY

NOVEL DESIGN TECHNIQUES (PLASMA, INK JET, ETC.) J. Ribera, Invest Plasma S.L.

Poligono Estadio, Nave 34. 12004 Castellon. J. Carda, Inorganic and Organic Chemistry dept, Campus

Riu Sec, Universitat Jaume I. 12080 Castellón

Spanish ceramic industry is one of the major world producers of ceramic tiles reaching annual production

volume of more than 600 million m 2 . Nevertheless currently high competition by other countries

can be observed. This makes necessary to introduce higher added value to the products, creating

new functionalities. One of the important areas of interest in near future is surface treatment with the

use of nanoparticles and thin-film technology and new processes in order to obtain functionally new

products with higher added value. In this respect a review of the traditional decorative techniques for

ceramic tiles, indicating the new possibilities of plasma-coating of metal and oxide coatings and laser

treatment with decorative purposes in order to create desired colour in situ. As well the ink jet technologies

and development of new nanoparticulate pigments development in the will be highlighted.

77


JUNE 27 TUESDAY AFTERNOON

JS1-TuA-INV.10 DECORATIVE COATINGS ON ENAMEL CERAMICS DEPOS-

ITED BY PVD TECHNIQUES. A. Alberdi. Fundación Tekniker. Avda. Otaola, 20. 20600

Eibar, Spain..F. Lucas, A. Belda. Fritta S.L. CV-20 Km 8, 12200 Onda (Castellón), Spain.Mª

José Orts. Instituto de Tecnología Cerámica (ITC). Campus Universitario Riu Sec, 12006 Castellón,

Spain

Ceramic tiles - floor tiles, wall tiles and other decorative articles - are usually made by firing a ceramic

backing, which is coated with a consolidated layer of frits and crystalline materials that glaze

after the baking process. The ceramic backing may be raw, as when the single-fire method is used,

or else baked, when the double-fire method is used.

Obviously, ceramic glazed products must have technical and decorative qualities that make them

suitable for the use to which they are to be put, such as hardness, resistance to cracking, wear and

scratching, imperviousness and insolubility in water and in those acids and alkalis with which they

may enter into contact in normal use. Decorative effects are created depending on the finishing

process used, for example, gloss or matt, opaque or transparent, smooth or granulated, polished, etc.

Modern decorative trends ask for conferring the tile a metallic appearance.

Current ceramic metallizing techniques normally consist of adding a given amount of metal to the

baked tiles, but prior to glazing or final enamelling, so their finishes have very low scuff and

scratching resistance, being impossible to use on floors or facades, and they are not resistant to

chemical attack. Furthermore, the gloss of current finishes does not exceed 200‰ at angle of incidence

of 60º.

Recently, new metallizing techniques have been developed using Physical Vapour Deposition

(PVD) methods. The authors set up a novel procedure to metallise enamelled products. Under vacuum

and after degassing the tile backing, a metallic coating grows on the enamelled tile surface by

bombardment with metallic ions and neutral atoms of titanium, zirconium, tantalum or chromium.

These atomic species are generated by a high intensity arc discharge (in the range 50-250 A) between

an electrode made of the metal of interest, normally a rod, pipe or plate, and an auxiliary cooper

electrode. Apart from pure metal films, nitrides and carbo-nitrides of these metals can be also

deposited on the tile surface by adding nitrogen and hydro carbide gases in the vacuum chamber.

Using this new procedure, enamelled tiles coated with 0.3 microns thick decorative films were produced,

which show attractive colours and metal appearance. Finishing colours depended on the

chemical nature of the film: golden (zirconium, titanium and tantalum nitrides), metallic grey (chromium

nitride, and pure Ti, Zr or Cr), reddish brown or purple (titanium carbo-nitrides). Apart from

the attractive colour, these decorative surfaces exhibit an outstanding metallic gloss (ZrN 736‰ at

angle of incidence of 60º), and excellent resistance to acids and alkaline substances.

Key words: Ceramic tiles, decorative coatings, physical vapour deposition.

.

76


JUNE 27 TUESDAY AFTERNOON

JS1-TuA-INV.9 HARD DECORATIVE METAL-OXYNITRIDE THIN FILMS PRE-

PARED BY PVD. F. Vaz, P. Carvalho.Departamento de Física, Universidade do Minho, 4800-058

Guimarães, Portugal.

The main objective of this work is the preparation of decorative zirconium oxynitride, ZrO x N y , thin

films by dc reactive magnetron sputtering. Film properties were analyzed as a function of the reactive

gas flow and were correlated with the observed structural changes. Measurements showed a systematic

decrease in deposition rate with the increase of the reactive gas flow and revealed 3 distinct

modes: i) metallic mode, ii) a transition mode and iii) an oxide mode. The measurements of target

potential were also consistent with these changes, revealing a systematic increase from 314 to 337 V.

Structural characterization uncovered different behaviors within each of the different zones, with a

strong dependence of film texture on the oxygen content. These structural changes were also confirmed

by resistively measurements, whose values ranged from 250-400 cm for low gas flows

and up to 10 6 cm for the highest flow rates. Color measurements in the films revealed a change

from bright yellow at low reactive gas flows, to red-brownish at intermediate flows and dark blue for

films prepared at the highest flows. Hardness measurements gave higher values for the region where

larger grain sizes were found, showing that the grain growth hardening effect is one of the main parameters

that can help explain the observed behavior. Also the peak intensity ratio and the residual

stress states were found to be important factors for explaining this behavior.

75


JS1 SESSION

74


TUESDAY AFTERNOON

73


JUNE 27 TUESDAY MORNING

WS-18-TuM-OR.10 A NEW PROCEDURE AND DEVICE FOR THE STUDY OF HY-

DRIDING PROCESSES FROM THE INNER SURFACE OF NUCLEAR FUEL CLAD-

DINGS. M. Díaz a , J. S. Moya a , J. L. Sacedón a* a Instituto de Ciencia de Materiales de Madrid

(CSIC), Cantoblanco, Madrid-28049, Spain. B. Remartínez b , S. Pérez b . b TEMAT Iberdrola, Pº

Virgen del Puerto, Madrid-28005, Spain

A new method and UHV equipment 1,2 that allows the study of the hydriding process of fuel claddings

from the inner surface is described. The hydriding is performed by heating the cladding in an

ultra-high vacuum chamber while hydrogen flows inside the tube. The external H 2 partial pressure,

the tube electrical resistance and the power dissipated by the reaction are measured throughout the

process. These measurements at different hydriding stages are complemented with an optical microscopy

analysis of the claddings give insight into the main physical processes 1 . As a consequence a

description of the hydriding first stages is provided. The method allows the measurement of the incubation

and failure times and the total energy dissipated by the hydriding reaction. In addition, useful

information about the kinetics of the hydriding process is obtained from external H 2 partial pressure

vs hydride rim thickness plot

This method has been applied to test the durability and reliability against the hydriding reaction of

commercial fuel claddings of zirconium alloys with different compositions and thermal treatments.

An additional study of the variation of Vickers hardness and elastic modulus with the stoichiometry

and thickness of the zirconium hydride rim formed inside this type of claddings has been carried out

by nanoindentation and XRD measurements. From these results it is possible to obtain some conclusions

about the mechanical stress distribution induced by the hydriding process and its influence in

the failure of these industrial elements.

1 Patent No.: US 6,873,672 B2

1 Patent No.: WO 2005/076286 A1

1

J. L. Sacedón, M. Díaz, J. S. Moya, B. Remartínez, J. Izquierdo, Journal of Nuclear Materials, 327 (2004) 11-18.

72


JUNE 27 TUESDAY MORNING

WS-18-TuM-OR.9 CALIBRATION OF HELIUM LEAKS: REFERENCE METHOD

AND DISSEMINATION. RANGE FROM 4.10 -14 MOLE.S -1 (10 -10 PA.M 3 .S -1 ) TO 4.10 -6

MOLE.S -1 (10 -2 PA.M 3 .S -1 ). Pierre OTAL, Frédéric BOINEAU, Jean-Claude LEGRAS. Laboratoire

National de Métrologie et d’Essais (LNE)

LNE developed in the last years a new method for the calibration of helium leaks. It is based on the

measurement of the pressure variation p due to the flow rate of the leak in a known volume. The

pressure is measured using a capacitance diaphragm gauge starting at about 3 Pa. A capillary leak is

calibrated as a function of the input pressure for both helium and nitrogen. The pressure variation allows

to creating a flow range over a decade.

Then the leak is supplied with mixtures of helium in nitrogen at different known concentrations

down to 100 ppm. The flow rate of helium is calculated from the total flow measured by the p and

the concentration measured in the LNE gas analysis laboratory. Different combinations of input

pressure and concentrations allow to defining step by step the flow scale down to 4.10 -14 mole.s -1 .

An uncertainty budget will be presented. The estimated uncertainty is ranged from 2 % at 4.10 -6

mole.s -1 to 5.5 % at 4.10 -14 mole.s -1 . Two methods are used for disseminating the measurements to

industry:

- A method by substitution, where the helium leak so defined is used to reproduce the same

output signal of a leak detector as observed with a working reference leak.

- A direct measurement of the client helium leak using the output signal of the leak detector.

In that case, the output signal is fitted as a function of the leak over 3 decades using 5 helium

leaks firstly calibrated.

Some results related to the linearity and the reproducibility of the leak detector will be given.

A comparison with another calibration technique developed for the low gas flow measurement has

been carried out in the higher part of the range. The agreement between the two methods operating

under vacuum for the first one and near the atmosphere for the other one was about 1 %, inside the

estimated combined uncertainty.

71


JUNE 27 TUESDAY MORNING

WS-18-TuM-OR.8 CURRENT TRENDS IN LEAK TESTING TECHNOLOGY

A. P. Fonseca, H. P. Marques, A. M. C. Moutinho and O. M. N. D. Teodoro. METROVAC – Laboratório

de Tecnologia e Metrologia de Vácuo. CEFITEC, Departamento de Física, Faculdade de

Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 CAPARICA, Portugal

Leak detection techniques are not of exclusive use of the vacuum scientist but are increasingly taking

their place in the demanding industrial environment. Accordingly, the definition of what is a leak

must also evolve to accommodate the points of view of the industry. A leak always involves a flow

of mass though the walls of a vessel. It usually results in an escape of liquids, vacuum or gases from

sealed components or systems.

Due to the demands of the electronics industry and increased activities in space exploration, the need

to develop new equipments and devices that had to be free of significant leakage appeared.

The maximum acceptable leak rate for a given product depends upon the nature of the product. In a

compact electronic device, like a photon multiplier, with a size of 2 cm 3 even a leak rate of 10 -

10 mbar l s -1 will be too high, producing a lifetime of only about 7 hours!

Leak detectors range in complexity from a tank of water, in which bubbles from a leak can be seen,

to highly sophisticated systems using radioactive tracer gases, depending on the leak detection technique

– e.g. acoustics, hydrostatic test, tracer fluids or gases, high voltage discharge. However, is the

application that defines the most appropriated method.

Commercial helium mass spectrometer leak detectors can commonly detect leaks down to 10 -10

mbar.l.s -1 range. Lower rates can appear from molecular permeation and not from orifices and therefore

are difficult to distinguish.

High sensitivity in commercial leak detectors is longer the most demanded requirement. Most developments

are being made in order to miniaturize the detectors as well as to fully automate its operation.

It has been developed a miniature mass spectrometer [ref MKS] with dimensions of

30x30x15 cm and weight less than 8 kg. With this kind of portable detectors it’s less time-consuming

to detect leaks in large vacuum systems that often require access to a great number of test points.

The latest published papers favour developments in acoustics detection technology for example Holland

et al describes a method for in-orbit identification and location of a leak in the International

Space Station using structure-borne ultra-sonic noise.

In this paper is work we summarize the most suitable leak detection methods according to the application

and the maximum admissible leak rate.

70


JUNE 27 TUESDAY MORNING

WS-18-TuM-OR.7 HEALIUM LEAKS TRACEBILITY AT CZECH METROLOGY

INSTITUTE (CMI). Dominik Prazak. Czech Metrology Institute, Okruzni 31, 638 00, Brno,

Czech Republic. Jiri Tesar. Czech Metrology Institute, Okruzni 31, 638 00, Brno, Czech Republic.

Petr Repa. Charles University Prague, V Holesovickach 2, 180 00, Prague 8, Czech Republic.

Ladislav Peksa. Charles University Prague, V Holesovickach 2, 180 00, Prague 8, Czech Republic.

Tomas Gronych. Charles University Prague, V Holesovickach 2, 180 00, Prague 8, Czech Republic.

Martin Vicar. Czech Metrology Institute, Okruzni 31, 638 00, Brno, Czech Republic.

The tightness of vacuum systems has very high and increasing importance in contemporary research,

industry and safety of work. Its consequence is continuous and growing demand for the calibration

services in this field.

Mass spectrometers as helium leak detectors are traditionally used for accurate measurement of vacuum

leaks. The critical point of their accuracy is their low long-term stability. It is necessary to calibrate

them with very short recalibration periods utilizing the secondary helium leak standards. But,

of course, these secondary standards need the traceability to the standards of higher order. Until recently,

CMI has used the services of other national metrological laboratories, but this system has

been becoming more and more insufficient.

So there has been decided to build our own primary standard of vacuum leaks in the framework of

United vacuum laboratory of CMI and Charles University – Prague. The recently finished high vacuum

standard based on continuous expansion has been chosen as the base leading to the reduction of

costs. That implies use of constant pressure - variable volume flow meter and comparative measurement

method. Its preliminary range is 3 . 10 -7 - 7 . 10 -4 Pa . m 3. s -1 with uncertainty less than 0.5 %, but we

study the possibilities of its extending. First of all it is needed in the lower range limit.

The paper will describe the problems that have occurred during construction (flow meter based on

bellows, its compression mechanism and measurement, reproducibility of its volume, pressure and

temperature stabilization and measurement, parasitic effects), the method of traceability and the attainable

uncertainties.

[1] ŘEPA, P., TESAŘ, J., GRONYCH, T., PEKSA, L., WILD, J.: Analyses of gas composition in

vacuum systems by mass spectrometry. Journal of Mass Spectrometry. 2002 (37), p. 1287-1291.

[2] PEKSA, L., GRONYCH, T., ŘEPA, P., TESAŘ, J.: Measuremet of the pressure differences in a

large chamber where the pressure is generated dynamically. Vacuum. 2002 (67), p. 333-338.

[3] PEKSA, L., ŘEPA, P., GRONYCH, T., TESAŘ, J., PRAŽÁK, D.: Uncertainty analysis of the

high vacuum part of the dynamic flow standard. Vacuum. 2004 (76), p. 477-489.

69


JUNE 27 TUESDAY MORNING

WS-18-TuM-OR.6 LEAK CALIBRATION BY COMPARISON WITH REFERENCE

STANDARD LEAKS. J. M. Hidalgo * and J. L. de Segovia ** * Telstar Industrial S. L., José Tapiolas

120, Tarrasa, Spain. ** Instituto de Ciencia de Materiales, CSIC, Cantoblanco, 28249 Madrid,

Spain.

e-mail: jldesegovia@icmm.csic.es/j.mhidalgo@telstar.es

For an industrial calibration laboratory the faster and reproducible method for helium leak calibration

is by comparing the leak to be calibrated with standard leaks already calibrated at a National

Calibration Laboratory or Accredited Laboratory, using a mass spectrometer tuned to Helium gas. In

the present work all the possible sources of uncertainties are discussed and they relative contributions

presented. Special consideration is given to the problem of the long term satiability contribution.

The optimal capacity of measurement is obtained according to the results obtained by application

of the specific calibration procedure.

68


JUNE 27 TUESDAY MORNING

WS-18-TuM-INV6.5 LEAK DETECTION: CALIBRATIONS AND REFERENCE

FLOWS ARE REQUIRED IN EVERY TYPE OF APPLICATIONS: PRACTICAL EXAM-

PLES. A.Calcatelli, Istituto Nazionale di Ricerca Metrologica, I.N.RI.M., Turin, Italy.M.Bergoglio,

Istituto Nazionale di Ricerca Metrologica, I.N.RI.M., Turin, Italy

D. Mari, Istituto Nazionale di Ricerca Metrologica, I.N.RI.M., Turin, Italy

Several methods and related instrumentation are used for leak detection from bubble emission to the

ultrasound devices, to pressure/vacuum variation measurements (vacuum gauges, thermal conductivity

sensors), to halogen leak detectors or detectors using radioisotopes, to the more recent instruments

based on selective ion pump detection (SIPD) and finally to the application of mass spectrometry.

The most diffused methods for the leak rates lower than 10 -3 Pa m 3 /s that is based on the

application of mass spectrometry with tracer gas (generally helium) is considered (MSLD). MSLD

represents the best choice for industrial control of tightening for its good sensitivity and obtainable

speed of testing. The leak test may be performed with various methodologies (vacuum, pressure or

vacuum-pressure) and its purpose may be to localize the leaks or to quantify them.

Leak detection is considered, at European level, by the WG 6 (leak testing) of the CEN/TC 138 (Non

Destructive Testing), and worldwide level by the SC 6 “Leak detection methods” of the ISO/TC 135

(Non Destructive Testing). At European level, several standards have been published regarding terminology

as well as the choice of the method or the calibration of a leak detector and calibration of

standard leaks.

If the leak detector output must have a real meaning in term of gas flow-rate the instrument has to be

calibrated and its uncertainty must be evaluated. Therefore, the calibration of a leak detector is performed

with reference to known gas flow-rates by using the so-called standard leaks both of permeation

or geometrical type (generally capillaries) which are used to generate flow from 10 -9 Pa m 3 /s

to 10 -3 Pa m 3 /s; these standard leaks are calibrated with reference to atmospheric pressure or vacuum

against primary gas flow-meters. The I.N.RI.M. primary flowmeters are shortly described which

cover the following gas flow-rate ranges:

• 2.10 -9 Pa m3/s e 2x10 -8 Pa m 3 /s with reference to vacuum, extended uncertainty 8%

• 2x10 -8 - 3.10 -5 Pa m 3 /s with reference to vacuum, extended uncertainty from 2% to 0.5%.

• 2.10 -5 Pa m 3 /s e 1.10 -3 Pa m 3 /s with reference to atmospheric pressure, extended uncertainty 2%.

Some calibration results are presented together with the preliminary results of a bilateral comparison

which is considered as preparatory for a more wide scale comparison.

A device devoted to on line control of components which need that all the significant parameters be

well defined starting from the mass spectrometer leak detector which is characterized from metrological

point of view, that is to say essentially for what concerns linearity and repeatability of the

out-put by using reference leaks. The whole machine must be well known in its working configuration

for what concerns linearity and repeatability and the traceability chain must be made evident.

67


WS-18 SESSION

66


JUNE 27 TUESDAY MORNING

JS1-TuM-INV.8 ADDED VALUE NANOSTRUCTURED COATINGS WITH TAI-

LORED OPTICAL BEHAVIOUR. C. N. Afonso. Instituto de Optica, CSIC, Serrano 121, 28006

Madrid, Spain.

Optical coatings are generally formed by multilayer films whose spectral transmission / reflection are

typically controlled through the number of layers, their refractive index and their thickness. However,

current applications demand more functionalities such as selective operation depending on input

conditions (intensity, polarization, etc...), tuneable or ultrafast response, and in many cases, several

functions in the same coating. The design of the structure of the coating in the nanoscale is an

attractive route to achieve this goal.

This presentation aims to show examples on how nanostructuring allows tailoring the properties of

the film or coating to the desired applications. It will first be illustrated through the production of

nanocomposite materials formed by metal nanoparticles embedded in a dielectric host that are known

to exhibit optical resonances due to dielectric or classical confinement effects. These effects are responsible

for colouring of many decorative glasses when the dimensions of the nanoparticles are

much smaller than the wavelength of the light. Whereas bulk techniques usually disperse nanoparticles

randomly, thin film technologies offer the possibility of organising nanoparticles in layers. This

layered structure can be then designed in order to achieve the desired response. This concept can

straightforwardly be extrapolated to other “dopants” such as ions or different hosts such as glasses or

ceramics. Examples will be given on how the optical response of nanocomposite films /coatings can

be tuned through the dimensions and separation of the nanoparticles, their “layered” distribution or

the use of different hosts. Finally, the possibility of incorporating different functionalities in the same

coating either through the use of different “dopants” or pairs “dopants”-host will be illustrated.

65


JUNE 26 TUESDAY MORNING

JS1-TuM-INV-7 COATINGS FOR OPHTHALMIC LENSES. T. Vilajuana, Departamento

de I+D+I INDO, Sta. Eulàlia, 181 08902 L’Hospitalet de Llobregat, Barcelona. Spain. E-mail:

toni@indo.es

Since 1937 Indo is the leading company in the ophthalmic optics Spanish market, and one of the five

main European companies of the sector. The core activity of the company is the fabrication of spectacle

lenses, which represents more than 50% of the total turnover. The investment in R&D activities

was 2.5% of the sales income in 2005 and is planned to increase an additional 4% in 2006.

The main requirements of an ideal ophthalmic lens, are lightness, transparency, scratch resistance

and impact strength. Additionally, an ideal lens should be as thin as possible. Organic or polymeric

lenses have a clear advantage in terms of weight and impact resistance when compared to mineral

glass. Nevertheless, a polymeric lens can be more easily abraded than a mineral one. Particularly,

high refractive organic lenses can easily be scratched. For this reason, the application of anti-scratch

coatings has become necessary to increase the abrasion resistance of polymeric lenses. Typically, that

coating is a few micron layer of a composite based on a polysiloxane matrix containing silica

nanoparticles. This provides the required flexibility and toughness to obtain good scratch resistance

and optimum adhesion of the coating to the lens.

An additional benefit of some lenses is that they adapt to light conditions, changing its transmittance

according to the amount of light outdoors. The benefit of this photochromic lenses is that they provide

a dynamic adaptation to light conditions and a UV protection. This is due to the presence in the

lens of molecules that react with UV radiation. The absorption of UV radiation changes the molecule’s

steric configuration, and consequently absorbing visible light. This is why the lens becomes

dark brown or grey, etc. This process is reversible and in the absence of UV light, the lenses become

clear. Some polymer lenses are casted mixing these photochromic molecules with the lens monomer,

while others are applied a photochromic layer in the external surface of a clear lens.

Lenses reflect light, since they consist of two optical surfaces that are immersed in an environment of

different refractive index. The higher the difference, the more light is reflected. This light reflected is

perceived as ghost images that superpose to natural perception and reduce the quality of vision,

which contributes to increase fatigue. These reflections can be practically be reduced with the application

of an antireflective (AR) coating, typically composed of 5 to 7 layers of metal oxides.

The first AR coatings easily got dirty and the smudges and fingerprints were more visible and difficult

to remove. In fact, many patients found it difficult to keep clean. The application of a hydrophobic

and oleophobic topcoat is a big advantage for these lenses, since they stay cleaner longer than

previous ones. The composition of that layer is based on a mixture of perluorated hydrocarbons and

silica compounds that repeal water and grease.

Since lenses are produced in large quantities, additional concerns like uniformity of optical and mechanical

properties are important key factors in order to decide which technology is used to produce

these coatings. Lens reflectance, abrasion resistance, coating durability, hydrophobicity and photochromism

has to be tightly controlled.

Developing new polymer materials with better optical and mechanical properties requires the application

of complex coatings and technologies. The production of millions of them at a competitive

cost and in a personalised basis is the challenge of the leading ophthalmic optical companies.

64


JUNE 27 TUESDAY MORNING

JS1-TuM-INV.6 SMART OPTICAL WINDOWS OF VARIABLE TRANSPARENCY. E.

Matveeva, Universidad Politécnica de Valencia (UPV), Centro Materiales y Tecnologías de Micro

Fabricación (MTM), Unidad Asociada al Instituto de Ciencias de Materiales de Madrid, Cami de

Vera s/n, E-46022 Valencia, España

The rare earth metals as well as its alloys with magnesium, or proper magnesium alloyed with iron,

nickel, manganese, etc. while being put into the contact with hydrogen form metal hydrides which

are wide-band semiconductors transparent in visible range of electromagnetic spectrum. Reversibility

of hydrogenation reaction allows for fabrication of the so-called Smart Optical Windows (SOW) that

change their reflectivity in function of external impact (application of electric field, change of intensity

of external light, change of temperature, etc.). The two approaches presently existed are hydrogenation

of alloys in gas phase and in liquid phase. The first process is performed in pure H 2 and allows

for achieving a long life-time, mere contrast of reflecting/transparent states and fair reproducibility

of results. However, it would need pumping the hydrogen in and out to the chamber where hydrogenating

metal is contained. Second approach is related with hydrogenation of alloys in liquid

phase under the cathodic bias. Alkaline solutions are mainly used as electrolytes for hydrogenation

(typically 1-6M KOH). This is due to the fact that those metals which possess hydrogenation ability

are stable at high pH values, while neutral or acid electrolytes provoke their fast oxidation. Examples

of electrochemical behavior of different hydrogenated materials will be demonstrated during the talk

together with the optical transformations accompanied the hydrogenation/ dehydrogenation processes.

The generalized design of the SOW with an electrical control consists of the two thin film electrodes

and a conducting media between them. The whole system must be sealed to assure functional stability

and integrity of the device similarly to devices used liquid crystals. One of the electrodes (principal)

is hydrogenated and another is the transparent auxiliary electrode that mainly serves as a means

to apply the potential. Due to limitations toward the electrolytes demonstrated by the principal electrode

(basic conductive media) the second auxiliary electrode must work at the same conditions: immersed

in 1-6M KOH. Indium-tin-oxide (ITO) gave firstly the impression to be a suitable candidate

for an auxiliary electrode in SOW. Nevertheless, its proper electrochemistry in basic electrolytes

governed by the mobility of the structural oxygen ions, deep reduction and changes in composition

and conductivity make the SOWs fabricated with ITO as an auxiliary electrode not reliable. Other

approaches to make conductive a transparent surface (glass/polymer) and exploit possibilities to fabricate

a sandwich-type device are analyzed.

In more advanced SOW technology the use of the polymeric conductive media has been demonstrated.

Nowadays, the polymeric electrolytes (or conductive ionic membranes) have extended applications

in hydrogen production, separation technologies and electrochemical synthesis. The key point

in the conductive polymers (membranes) is the formation of the highly extended and penetrated network

of the conductive nano-metric ionic passes formed from the overlapped solvated (hydrated)

shells of the functional (acid) groups attached to the polymer chains. The dual character of the resulted

material (consistency of polymer and conductivity of electrolyte) offers new options in SOW

fabrication. The device implemented the Nafion membrane soaked in water and other solvents

showed an acceptable working voltage, good transition to the transparent state and satisfactory lifetime

under cycling.

The principal sources for instability and device destruction are discussed based on the experience acquired

in the MTM Center of the UPV.

63


JUNE 27 TUESDAY MORNING

JS1-TuM-INV.5 TAILORING THE OPTICAL PROPERTIES OF THIN FILMS DE-

POSITED BY PLASMA CVD. A. Barranco, A. Borrás, F. Gracia, A.R. González-Elipe. Instituto

de Ciencia de Materiales de Sevilla (CSIC-Universidad de Sevilla), c/Américo Vespucio s/n 41092

Sevilla Spain.

Plasma Enhanced Chemical Vapour Deposition (PECVD) and plasma treatments are being increasingly

used for the fabrication of optical films and coatings. The technique offers a wide ranging control

of plasma surface interactions, high deposition rates and conformal depositions being fully compatible

with the existing silicon based semiconductor technology and scaleable from the laboratory to

the industry. These materials are obtained in the form of single thin films, multilayers, graded index

layers, nanocomposites, patterns, and others for applications such as optical filters, antireflective

coatings, optical waveguides, wavelength shifters, optical sensors, etc. For these applications is critical

the control of the chemical composition and the microstructure of the deposited films.

Novel methodologies for the synthesis of optical thin films using plasmas will be presented. The examples

cover the control of n and k values in organosilicon thin films, the use of sacrificial polymeric

layers to tailor the microstructure of oxide films deposited at room temperature and the microstructural

control of TiO x and MO x /TiOx optical films. Besides, a novel type of organic and nanocomposite

fluorescent films deposited from laser dyes will be discussed. These highly functionalized

thin films are the basis of a novel photonic materials technology (i.e., photonic filters and sensor on

a chip devices).

.

62


JUNE 27 TUESDAY MORNING

JS1-TuM-.INV.4 FUNCTIONAL AND DECORATIVE REFLECTING LAYER

FOR AUTOMOTIVE LIGHTING IN VALEO. J. M. Trigo, R. Acuña, A. Lara and D. Teba,

Valeo Iluminación Martos, Calle Linares 15, 23600 Martos, Jaén. Spain.

The possible developments of metallization process for reflectors are restricted looking for the quality

(maintaining process parameters under control to avoid scraps, creating effective hydrophilic layers

to diffuse more an more fogging materials, homogenizing layers thickness) and productivity (reducing

cycle time, simplifying process steps, decreasing costs and so on).

Following the lean process design rules, the trend is to use short dimension machines as Pylonmet

(Leybold TM) having short cycle times for PECVD, employing classical materials, as Al for reflective

layer and silicone matrix starting from the monomer hexamethyl disiloxane as protective topcoat.

This new concept has the advantages of the sputtering system (material long life, good process

control for product quality consistency, better adhesion with higher layer density) and the advantages

of batch metallization (parts movement and unique chamber).

Many efforts are focused to multiply the decorative possibilities of bezels, some of them without reflective

coatings (mass coloured materials where decorated part is obtained directly by injection of

pigmented thermoplastics); some others employ coloured reflective coatings by changing the metal

itself, creating different chemical reactions with the same metal, giving different colours or with coloured

topcoat.

Paint is an usual choice to give decorative effects on bezels because the metallized pigments give us

some shining appealing surfaces. On some cases, competitive costs can be achieved in front of in

chamber metallization process. Less original effects are achieved masking partially part areas resulting

delimited lines between metallized and non metallized where is visible the natural colour of base

plastic.

The interaction of YAG laser (wavelength on near IR) and reflective coatings, bring us new and

original possibilities for decoration purposes, because laser removes the reflecting layer showing all

kind of patterns by contrast with coloured plastic substrate.

61


JUNE 27 TUESDAY MORNING

JS1-TuM-INV.3 MULTILAYER COATINGS FOR OPTICAL AND ENERGETIC

CONTROL IN GLASSES. F. Villuendas. Departamento de Física Aplicada. Universidad de

Zaragoza. 50009, Zaragoza. Spain

Architectural trends in the last century drove the use of glass façades in construction, since they provide

a lightness aspect to the building, allow the inside-outside communication though the façade and

admit a great variation in the aesthetic aspect. However, the use of glass façades presents several disadvantages,

in particular energetic disadvantages, caused by energy conductive losses with values of

5,7 W/m 2 K in monolithic glass, and by the overheat produced by the excessive solar gain, with values

until 500 W/m 2 in south orientation.

The use of insulating glazing including multilayer sputtered coated glass avoids most of these inconveniences,

giving rise to the development of new products with optimized performances of thermal

isolation and energetic solar transmission. So, sputtering technologies and procedures for large area

glass coatings will be reviewed as the first point in this presentation.

Several coatings have been designed for optical and energetic control in buildings that are often included

in two big groups, solar control coatings that reduce solar transmission of the glazing and

low-emissivity coatings that reflect infrared radiation while they transmit visible light. Optical and

energetic characteristics are determined by absorptive and infrared reflective properties of metallic

layers together with interference conditions in dielectric layers, so that optical and energetic properties

will be dependent on material composition, multilayer structure and thickness of different layers.

Typical multilayer structures for both solar control and low-emissivity coatings will be presented,

showing the optical and energetic characteristics that can be achieved.

The design and development of new multilayer structures with specific energetic and optical properties

is the aim of research activities in our group, that has been carried out in collaboration with the

company Ariño-Duglass. Finally, we present the main features of the design and fabrication processes

followed for the development of several specific purpose coatings, including solar control and

low-emisivitty properties, with improved characteristics of different kinds as those concerning energetic

behaviour, thermal isolation, aesthetic aspect, colour reproduction or chromatic coordinates.

60


JUNE 26 TUESDAY MORNING

JS1-TuM-INV.2 SURFACE TREATMENTS FOR INDUSTRIAL GLASSES J.M. Marco.

Responsable de I+D. Ariño Duglass S.A. La Puebla de Alfinden, Zaragoza. Spain

Glass, as architectural material, has extraordinary characteristics against other transparent materials

in relation to its durability and technical performances. In addition of the intrinsic material characteristics,

glass is subjected to different transformation processes in order to achieve a final product that

fulfils all the requirements demanded in actual architecture. Improvements in mechanical resistance,

safety against breakage, thermal isolation or solar control, are reached by means of several kinds of

treatments. Some of these important performances are only possible through surface processing technologies.

In this presentation, a general overview of the main manufacturing process for industrial glass will be

exposed, underlining the common surface treatments used in this sector. A brief introduction to

products manufactured by pyrolysis and sputtering in order to improve the solar control and thermal

isolation will be presented, exposing real application and performance achieved.

Another important requirement that glass must fulfil is the control over its aesthetic aspect. Application

of paints and enamels by silkprint, roll coating or digital inkjet systems allows to modify the

colour, texture and visual aspect of glass, customizing each architectonical project. Last developments

in float glass decoration and direct application of these products will be presented.

Also, laminated glass technologies give the opportunity to modify the general behaviour of glass, in

this sense it is possible to incorporate a coated or decorated PET that expands the uses of glass. The

possibility to integrate liquid crystal polymers in laminated glass open a way to produce active windows.

Finally, a prospect about new developments expected in the sector will be outlined.

59


JUNE 27 TUESDAY MORNING

JS1-TuM-INV-1 REACTIVE SPUTTERING OF METAL OXIDES AND NI-

TRIDES FOR INDUSTRIAL APPLICATIONS. Victor Bellido-González, Benoit Daniel,

Sarah Powell GENCOA, Physics Road, Liverpool L24 9HP (UK). E-mail: victor@gencoa.com

Magnetron sputtering has become one of the key industrial vacuum coating technologies in regards

to many of today’s applications. In magnetron sputtering, a material called target (e.g. Ti),

suffers ion bombardment by ions of a mainly inert gas (e.g. Argon) and in that bombardment material

is removed and transported onto a desired surface to be coated. The plasma trap around that

target is based on a electric-magnetic cross field (ExB). Some of these processes also involve the

reaction between the element or elements of the target material and a gas. That reaction produced

a coating of very different nature to the target material itself and the process is called reactive

magnetron sputtering. Two groups of these reactive gases are Nitrogen which will give as a result

a nitride of the elements of the target (e.g. TiN) and Oxygen which will give as a result an

oxide of the elements of the target (e.g. TiOx). In some cases the target itself is of a oxide or nitride

nature and generally some sort of degree of reactive sputtering is maintained in order to taylor

specific coating properties (e.g. Ito target sputtering in atmospheres containing O 2 or H 2 ). In

this presentation some of the current issues in the control of such processes will be exposed. Also

practical applications of oxides and nitrides will be explained based on our industrial experience.

These will include multilayer oxides for optical coatings, transparent conductive oxides for

photovoltaic and display technology, oxides for scratch resistance technology, nitrides for decorative

and hard coat applications, solar-thermal absorbers, etc. A short comparison with some

other technologies such as cathodic arc will be exposed as these technologies can be sometimes

found competing on a similar ground of applications.

58


JS1 SESSION

57


JUNE 27 TUESDAY MORNING

TuM-Pl.2 THE ROLE OF ENERGETIC IONS IN THE DEVELOPMENT OF MUL-

TILAYERED X-RAY REFLECTION OPTICS. J. Verhoeven, FOM AMOLF, Kruislaan

407, 1098SJ Amsterdam, The Netherlands

Since the seventies of the past century multilayer systems at nanometre scale have been applied

as spectroscopic elements for wavelengths > 0.1 nm as well as optical reflection systems in the

short wavelength region (


PLENARY

55


TUESDAY MORNING

54


JUNE 26 MONDAY AFTERNOON

WS-18-MoA-OR 5 DYNAMIC EXPANSION SYSTEM AT CEM. C.Matilla;

N.Medina; S.Ruiz. Spanish Centre of Metrology (CEM).

The Spanish Metrology Centre has an orifice-flow primary pressure standard. In this kind of pressure

standard a known flow of gas passes through an orifice of calculated conductance creating a pressure

gradient between both sides of the orifice. The known flow of gas is generated by a precision flowmeter

which can work using the constant volume method or the constant pressure method. Since its

construction the system has suffered several modifications in order to improve its results which will

be described as follows.

The first flowmeter was manually operated. That is the reason why it could basically be used with

the constant volume method. Nowadays it has been completely automatised

and it uses the constant pressure method, which is much more accurate. Data acquisition software

has been designed to monitor all the parts of the system involved. Some parts of the flowmeter have

been correctly isolated by means of aluminium walls to stabilise their temperature.

The first vacuum pump connected to the vacuum chamber was a 300l/s turbomolecular pump. At

present it has been replaced by a 700 l/s turbomolecular pump which allows the system to be closer

to ideal conditions as well as to obtain an appropriate base pressure more easily.

53


JUNE 26 MONDAY AFTERNOON

WS-18-MoA. OR.4 LONG TERM SHIFT IN CAPACITANCE GAUGES: CONTRIBUTION

TO THE TOTAL UNCERTAINTY. J. M. Hidalgo * and J. L. de Segovia** Telstar Industrial S.L.

José Tapiolas 120, O8226 Terrassa Spain. ** Instituto de Ciencia de Materiales,CSIC,Cantoblanco,28240Madrid,Spain

e-mail:jldesegovia@icmm.csic.es/j.mhidalgo@telstar.es

One of the contributions to total uncertainty in capacitance gauges is the shift of long-term stability.

This contribution can be only determined by recalibrations usually with a periodicity of one year. In

the present work, we present a study of the “shift” of four capacitance manometers ranging from 1000

mbar to 10 -3 mbar. Recalibration of the reference standard took place at two National Laboratories

with one-year periodicity and for a total time up to six years depending of the gauge. This is an

enough extended period to obtain some conclusions about the long-term stability in this kind of

gauges. Based on their principle of working the higher contribution to the “shift” is expected from the

fatigue of the material of the membrane. The deviation i.e., the difference between the readings of

working standard of the National Laboratory and the calibrating gauge, are also discussed. The several

contributions to the total uncertainty are presented and compared with the uncertainty due to the shift.

As consecutive recalibrations are not performed at the same calibrating points in the primary standard

of the National Laboratory, it is necessary to perform interpolations to obtain the differences of the

readings at the same calibrating points, uncertainty considered in the final expanded uncertainties

52


JUNE 26 MONDAY AFTERNOON

WS-18-MoA.INV.4 CALIBRATION OF PRESSURE SENSORS IN AN INDUSTRIAL

ENVIRONMENT. M. Wüest, INFICON Ltd., Alte Landstrasse 6, LI-9496 Balzers, Liechtenstein

National Measurements Institutes calibrate vacuum pressure sensors a few gauges at a time in a laborious

and time consuming fashion resulting in an accurate calibration with small error estimates. A

manufacturer produces a comparatively large number of sensors a day which must be economically

calibrated. Therefore, a manufacturer of vacuum pressure gauges can not spend the same amount of

time at a calibration. Here, we describe a procedure to calibrate vacuum gauges rapidly and cost efficiently.

Maintaining the calibration in an industrial environment is another challenge. Vacuum

gauges are calibrated in the factory in a clean environment with nitrogen. However, during the use of

the gauge, the sensor may encounter an environment which causes coating or etching of sensor elements.

This leads to degradation of the sensor with time and inaccurate pressure readings, but may

be difficult to detect. I will describe examples of contamination and some of the counter measures.

51


JUNE 26 MONDAY AFTERNOON

WS-18-MoA-INV.3 CLEANING PROCESSES AND QUALITY CONTROL FOR VAC-

UUM. R J Reid, ASTeC, CCLRC Daresbury Laboratory, Warrington WA4 4AD, UK

Cleaning is an important part of the processing of vacuum components and systems for any level of

vacuum. However, the lower the pressure required, the more stringent the cleaning requirements

must be.

Over recent years, many of the traditional processes used for cleaning have become unacceptable because

of their effect on the environment and, indeed, many have been prohibited by legislation.

In this paper, an outline will be given of the search for the “perfect” cleaning process for UHV and

XHV components which is effective, economical and likely to remain acceptable. We shall discuss

what has become the industry standard use of aqueous detergent based techniques and the use of

some of the newer solvents which have been developed.

Of course, the search for a “perfect” process leads us to pose the question “How do we know when a

system is sufficiently clean?” Some answers to this question will be discussed. This will then lead us

to look at implementation of quality control procedures to ensure that an “as delivered” component

will be satisfactory for purpose.

Examples will be given, including that of a very large XHV vessel currently being manufactured in

Germany.

50


WS-18 SESSION

49


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.16 DUAL DC MAGNETRON CATHODE CO DEPOSITION OF (Al,

Ti) AND [(Al, Ti) N] THIN FILMS WITH CONTROLLED DEPTH COMPOSITION. Y.

Nunes, A. Wemans, H. P. Marques, Q. Ferreira, O. M. N. Todoro and M. J. P. Maneira. Cefitec -

Department of Physics, Faculty of Sciences and Technology, New University of Lisbon, P-2829-

516, Caparica, PORTUGAL.

Recent publications show that [(Ti, Al) N] thin films produced with direct current reactive magnetron

sputtering can significantly improve electrochemical and biocompatibility properties of the base

metal alloy. The purpose of this work is to study the characteristics of titanium-aluminium nitride

[(Ti, Al) N] films produced using a novel coating technique.

Thin (Al, Ti) films with a linear gradient depth composition are obtained from a custom made codeposition

system which employs pure Al and Ti sputter targets. Two direct current magnetron cathodes

with independent plasma sources are simultaneous controlled by custom LabView software

which allows real-time and independent control of the deposition parameters for both cathodes.

Two types of gradient thin films were produced. Starting with 100% Al at bottom and 100% Ti at

surface and starting 100% Ti and ending with 100% Al at surface. Both types of films are of 500nm

thin. Depth profile was acquired using secondary ion mass spectrometry (SIMS). These films of (Ti,

Al) and [(Ti, Al) N], have been grown onto Mg, Glass and Si (100) substrates, the first in argon atmosphere

and the later in nitrogen.

Further analysis will be carried using atomic force microscopy to investigate the surface morphology

and X-ray photoelectron spectroscopy (XPS) in order to detect possible chemical interactions between

the film compounds.

48


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.15 OXIDE THIN FILM COATINGS BY SPRAY PYROLYSIS

ONTO STEEL COILS. R. López Ibáñez. Departamento de Física Aplicada I, Facultad de Ciencias,

Universidad de Málaga, E-29071 Málaga, Spain. F. Martín. Departamento de Igeniería Química,

Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain. J.R. Ramos-Barrado. Departamento

de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga,

Spain. D. Leinen. Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga,

E-29071 Málaga, Spain.

A large scale spray pyrolysis coater has been designed and constructed for industrial pilot trials in

the aim of depositing different functional metallic oxide thin films onto metallic substrates, such as

antireflective layers, self-cleaning films, barrier layers, selective thin films, photocatalytic coatings,

etc. Within the field of solar thermal energy, a zirconia film has been produced onto an aluminized

steel coil of 0.4 m width which has been previously coated with a selective layer elsewhere. The zirconia

film as a top-coat has the function of anticorrosion and protection against ambient impact in

outdoor conditions.

Technical details: Zirconium acetyl-acetonate in a 0.02 molar aqueous solution was used as precursor

for spraying onto the 200º C heated substrate, growing in these conditions aproximately a 10 nm

thick zirconia thin film. After several coating repetitions an 80 nm ZrO 2 thin film was produced.

Characterization: UV-Vis-NIR-MIR hemispherical reflectance spectroscopy showed that the zirconia

coating is highly transparent and acts as an antireflection layer, increasing the solar absorptance in

about 10 %, but not degrading the thermal emittance at 373K, thus improving optical properties for a

solar thermal device. SEM revealed a dense film which covers well the substrate sealing existing

pores. No cracks could be seen on the surface of the coating even after repeating the coating process

for several times, rolling up and unrolling the steel belt from its cylindrical storage. XPS depth profile

analysis showed that the material was well pyrolysed to zirconium oxide. Only 3% of carbon remaining

from the precursor was found inside the film, stabilized in a ZrC phase homogeneously diluted

across the zirconia film thickness. No crystalline structure was detected by XRD. Linear polarization

measurements were carried out in 0.5 molar sodium chloride aqueous electrolyte solutions.

A reduction in the registered current densities showed a decrease in corrosion attack by approximately

one order of magnitude when comparing to the corrosion behaviour of the substrate itself.

Conclusions: Compact, homogeneous and well synthesized zirconia thin films have been deposited

onto a continuously moving steel belt with an industrial scale spray pyrolysis pilot station. The zirconia

film improves corrosion resistance and the optical properties of the layer stack, zirconia topcoat,

selective layer, aluminized steel substrate, with regard to solar thermal applications.

Acknowledgements: Funds from the EU (project SOLABS: ENK6-CT2002-00679) are gratefully

acknowledged.

EU Project SOLABS: Development of unglazed solar absorbers (resorting to coloured selective coatings on steel material)

for building facades, and integration into heating systems. www.solabs.net

47


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.14 STUDY OF THE EFFECT OF SILICON EXCESS AND ARTIFI-

CIAL AGEING ON THE MICROSTRUCTURAL STABILITY OF Al-Mg-Si ALLOYS. Y.

Aouabdia*, Boubertakh ABDEL HAMID*, Hamamda SMAÎL*. * Laboratoire des Propriétés Thermodynamiques

et des Traitements de Surface des Matériaux. Faculté des Sciences, Université Mentouri-Constantine

Route Ain El-Bey, 25000 Constantine, Algérie

aouabdiayoucef@yahoo.fr

The use of Al based alloys for automotive body materials has been driven by a number of issues, in

particular weight saving. We are interested in in Al–Mg–Si alloys with excess Si. For this work, we

study the effect of excess Si on the precipitation of the β’’ phase. Samples from an Al–Mg 2 Si–0.5%S

were studied by differential scanning calorimetry (DSC), optical microscopy, Vickers hardness test

ing, and MEB. Data on reaction kinetics, grain size, and micro-hardness are analyzed with reference

to a stoichiometric alloy. This study revealed that excess Si increases the activation energy for the re

action, and globally improves the mechanical properties of the alloy. The precipitation sequence in the

Al-Mg-Si alloys with excess silicon is generally accepted to be:

clusters of solute atoms GP zone IGP zone II/ β” β’ β (Mg 2 Si)+Si

Key words: Al–Mg– Si alloys, excess Si, precipitation, activation energy, β'

46


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.13 BREAKDOWN VOLTAGE IN MAGNETRON DC GLOW DIS-

CHARGES. THE INFLUENCE OF THE MAGNETIC FIELD. Y. Nunes, A. Wemans, P. R.

Gordo and M. J. P. Maneira. Cefitec - Department of Physics, Faculty of Sciences and Technology,

New University of Lisbon, P-2829-516, Caparica, PORTUGAL.

In abnormal glow discharges with magnetic field, the electrons are confined in a trap near the cathode

allowing work at lower pressures and voltages. For thin film applications this can influence positively

the quality of the sputtered film and decreases the processing time.

d

Fig1. Cathode mounted in the system

and the copper discharge on argon.

Fig2. Magnetic circuit position inside

the cathode body

In this work breakdown voltages of the abnormal glow discharges of argon on copper with magnetron

assistance, are measured for different magnetic configurations.

To achieve this, a cathode, shown in Fig.1, was constructed with a magnetic circuit, based on permanent

NdFeB, which can be systematically moved allowing fine control of magnetic field distribution,

see Fig.2. This way the influence of the magnetic field in the plasma parameters and in particular the

influences in the breakdown voltage are studied.

The breakdown voltages are measured and presented as a function of pressure for different distances

of the magnetic circuit to the target. The study takes in account a range of pressures from 0.2 to 32

Pa and a range of the parallel component of the magnetic induction, from 0.3 T to 1.7 T at the target

surface.

The expression,

V ( P)

= C ⋅e

B

1

P


C2

+ C + C ⋅ P

3

4

fits the data of breakdown voltage dependence on the working pressure, with high correlation coefficient

and the constants depend on magnetic distribution

At each magnetic configuration the first exponential term accounts for low pressure range and the

linear term accounts for the higher pressure range. Minima similar to what happens in Paschen’s

Law, are observed which shifts to lower pressure with increase of the magnetic field. This behavior

is systematic and regular.

45


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.12 STRUCTURAL, ELECTICAL AND OPTICal PROPERTIES OF

INDIUM-TIN-OXIDE THIN FILMS preparED by pULSED LASER DEPOSITION. A.

Khodorov, M. Piechowiak* and M.J.M.. Gomes. Physics Center, University of Minho, 4710-057

Braga, Portugal. *Department of Material Science, University of Silesia, 41-200 Cosnowiec, Poland

Indium-tin-oxide (ito) films show an interesting and technologically important combination of properties:

excellent substrate adherence, hardness, chemical inertness, good electrical conductivity and

high transparency in the visible range of electromagnetic spectrum. for using ito films as transparent

electrodes to grow multilayer structures the crystalline quality and preferred orientation of domains

in the films are very important.

In this work we prepared ito thin films by pulsed laser deposition at different temperatures (from 24

up to 600 o c) with several oxygen pressures on glass substrate. the texture selection and cell parameters

were studied with help of x-ray diffraction. the sheet resistance was determined by a four-pointprobe

method at room temperature. the optical properties were examined in the wave-length range

200 - 3200 nm. the dielectric function of ito film was obtained by fitting the measured transmission

and reflection spectra to a dispersion relation, which combines the drude model and lorentz oscillator.

the well crystallized, highly textured and highly transparent films were grown at high temperatures.

variation of substrate temperature as well as oxygen pressure during deposition results in different

structural, electrical and optical properties. the correlation between deposition conditions and

physical properties of ito films was observed and analysed.

This work was supported by fct (grant sfrh/bpd/11675/2002)

44


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.11 ADSORPTION PROPERTIES, MICROSTRUCTURE AND OP-

TICAL BEHAVIOUR OF TIO 2 THIN FILMS PREPARED BY PECVD. A.Borrás, A. Barranco,

J. Cotrino, A.R. González-Elipe. Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ.

Sevilla). Avda. Américo Vespucio s/n. 41092 Sevilla (Spain)

It is a common place that the type of microstructure of thin films is critical for an effective control of

their optical properties. Usually, the microstructure is monitored by direct observation by SEM and

related microscopies. Recently, the use of spectroscopic ellipsometry under controlled ambient conditions

to measure adsorption isotherms has become an interesting technique to asses the type of porosity

in the films. In the present paper we discuss the possibilities of the adsorption isotherm technique

measured by means of a quartz crystal monitor (QCM) to asses the porosity of TiO 2 thin films

prepared by PECVD under different conditions. The microstructure and optical properties of the

films have been also characterized by SEM and optical methods. A large variety of TiO 2 thin films

with different microstructures and optical constants (n ranging from 1.8 to 2.2) have been obtained.

SEM gives information about the type of microstructure developed in the films (columnar, globular,

homogeneous, etc.). In addition, the water isotherms measured with the QCM provides important information

about the type of pores present in the films (i.e., micro, meso or macro pores) and the pore

size distribution. The analysis of the reversibility of the adsorption processes, as well as the dependence

of the adsorption characteristics as a function of the thin film thickness, have furnished important

clues to explain the optical properties of the films and their dependence on thickness. Small

variations of the optical constant of thin films exposed to the atmosphere can be also explained by

realising the irreversibility of some of the adsorption processes under ambient conditions.

The use of adsorption isotherms of vapours to characterize the porous structure of thin films can be

considered as an universal tool for the porous characterization of these materials providing complementary

information on the microstructure of the films

43


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.10 THE INFLUENCE OF MAGNETIC CONFINEMENT IN DI-

RECT ABNORMAL GLOW DISCHARGES. Y. Nunes, A. Wemans, P. R. Gordo and M. J. P.

Maneira. Cefitec - Department of Physics, Faculty of Sciences and Technology, New University of

Lisbon, P-2829-516, Caparica, PORTUGAL.

In this work an experimental study of the magnetic field influence on planar magnetron abnormal

glow discharges of argon on copper targets is presented. A magnetron cathode that allows the control

of the magnetic configuration was developed, and its magnetic circuit characterized.

To quantify the magnetic field influence in the discharge, a confinement power parameter C B , was

defined. This parameter, takes into account simultaneously the useful volume of the field, V C , and

the average of the parallel component of the magnetic induction to which the plasma is subjected.

For a planar magnetron cathode with cylindrical symmetric magnetic field, where r and z are the radial

and height coordinates, and B || the parallel component of the magnetic field in this coordinate.

The confinement power parameter is:

C

∫∫

B

= 2 π

||

)

V C

B ( r,

z rdrdz

Current-voltage-pressure characteristics were measured and the influence of the confinement power

is mapped through current-voltage curves at constant confinement power values, displayed at several

pressures. It was showed that at higher confinement power values the behaviour of the I-V characteristics

is in general well described by the Thornton empirical law, I=kV n .

Systematic study of k and n Thornton parameters with confinement power will be presented. The results

show that above certain value of C B, the Thornton parameter, n, that is considered to characterise

the entrapment efficiency of the electrons, converges to a constant for pressures from 1 to 8 Pa, as

can be seen in Fig1.

Fig.1 – Thornton parameter

n as function of confinement

power C B.

The data shows also that there is dependence between n and k, Thornton parameters.

42


JUNE 26 MONDAY AFTERNOON

RIVA-TF-MoA-OR.9 INFLUENCE OF PRESSURE ON THE STRUCTURAL ME-

CHANICAL AND DECORATIVE PROPERTIES OF TiN THIN FILMS DEPOSITED BY

CATHODIC ARC EVAPORATION. A. Lousa, J. Esteve. Departamento de Física Aplicada y

Óptica, Universidad de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya, Spain. J.P.

Mejia, A. Devia. Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales,

Campus La Nubia, Manizales, Colombia.

Titanium nitride TiN is one of the hard materials most widely studied and commonly used as decorative

coatings, wear-resistant coatings, diffusion barriers and electrodes in industrial applications. TiN

coatings are deposited by different PVD and CVD deposition techniques. The typical gold color of

TiN makes it an attractive candidate for decorative applications. TiN can be obtained in a relatively

wide range of compositions around stoichiometry. Changing the stoichiometry around the 1:1 composition

broadens the spectrum of colors and can modify the mechanical properties compared with

those of stoichiometric TiN.

Cathodic Arc Evaporation (CAE) is a especially attractive PVD deposition technique both for its

unique abilities (highly ionized vapor which allows ion energy control through substrate bias voltage,

high deposition rates, excellent adhesion), and for been widely use in industrial applications. It

is well known that composition, structure and properties of the deposited films depend on the process

parameters such us growth temperature, substrate bias voltage, gas pressure in the vacuum chamber.

The purpose of this work is to study the feasibility of depositing TiN coatings of different gold tones

with good mechanical properties by using a metallic Ti cathode and varying the nitrogen partial pressure

in a CAE reactive process. This pressure was varied between 5x10 -4 and 3x10 -2 mbar. The other

technological parameters were kept fixed for all the samples at the following values: cathodic current,

60 A, substrate temperature 400 ºC, substrate bias voltage, -300 V. The coatings were deposited

on polished steel substrates.

The resulting film thickness varied between 1-2 microns, with high deposition rates which ranged

from 8 μm/h for the samples deposited at low pressure, to 4 μm/h for the samples deposited at high

pressure. The composition of the coatings studied by XPS indicates an increasing nitrogen content as

the nitrogen partial pressure is increased. SIMS analysis shows that this composition is uniform

throughout the coatings thickness. The crystalline structure was studied by XRD which shows typical

diffraction patterns corresponding to polycrystalline TiN. The evolution of the crystalline structure

with pressure is discussed in terms of grain size and preferred orientation. The color characteristics

of the samples were analyzed by spectral reflectometry in the visible range. The reflectivity

spectra show a gold-like shape with significant shifts that correlates to the nitrogen content in the

samples. The mechanical properties of the coatings were characterized by dynamical nanoindentation

(NanoTest 550, Micro Materials Ltd.) with a Berkovich diamond tip. The hardness and Young’s

modulus values were obtained by the Oliver and Pharr analysis method. The Young modulus values

resulted close to the bulk TiN value (310 GPa). The hardness of the coatings increases with nitrogen

pressure until reaching a maximum of 24.5 GPa at 1.3x10 -2 mbar, in the intermediate zone of the

studied range, and decreasing for higher pressures.

In summary, we have shown that the control of the nitrogen pressure is useful to obtain TiN coatings

with a wide palette of gold colors and good mechanical properties.

41


RIVA-TF SESSION

40


JUNE 26 MONDAY AFTERNOON

ETCHC-MoA-INV.3 THERMAL BEHAVIOUR OF W-SI-N HARD COATINGS IN

PROTECTIVE AND OXIDATION ENVIROMENTS. A. Cavaleiro, ICEMS -Faculdade de

Ciências e Tecnologia da Universidade de Coimbra, Dep. Eng. Mecânica, Rua Luís Reis Santos,

3030-788 Coimbra, Portugal

Extensive discussion has been raised concerning the structural arrangement in TM-Si-N

(TM=transition metal) nanocomposite coatings, particularly on the way how Si is present in the coatings.

Furthermore, abundant results on the hardness and Young´s modulus of these films is available

in the literature, particularly for TM = Ti and Zr. As a function of the phase arrangement, different

interpretations and discussions on the hardening mechanisms involved in the mechanical behaviour

of the coatings, have been raised such as, grain size, residual stress, lattice distortion. Many authors

defend that the hardness of TM-Si-N films depends only on the purity, dimensions and distribution

of the Si-N phase in relation to the TM nitride grains.

W-Si-N is a particular case in the world of TM-Si-N systems (TM=Ti, Zr), due to the different

chemical affinity among the elements. In fact, the affinity of N for W is much lower that the one of

Si, inversely to the case of e.g. Ti-Si-N where similar affinities of Ti and Si for N are observed. Such

a fact determines the arrangement of the phases during the deposition and has a huge influence on

the structural stability of the coatings when annealed at increasing temperatures. The main consequences

are: (1) much higher N 2 partial pressures are needed for depositing films with W-nitride

phases and (2) after thermal annealing no W-nitride is detected in the films. However, the coatings of

this system can also show hardness values as high as 45GPa even if the main phase (W-based) his

typically a metallic bonding type based material..

In this talk, the current knowledge on the thermal annealing of W-Si-N sputtered films in both protective

and oxidant atmospheres is reviewed. Firstly, sputter deposited single W films are presented

as a particular case of metallic element films and their thermal annealing analyzed. The transition for

the W-Si-N films permitted to conclude that the addition of Si promotes a loss of the crystallinity degree

until amorphous structures are reached. Generally, amorphous coatings (20-30GPa) are softer

than crystalline ones (25-45GPa). Afterwards, the thermal stability of W-Si-N coatings is considered

either in protective or oxidant atmospheres. Special attention is paid for amorphous films. In protective

atmosphere, it is shown that after crystallization the hardness can be higher than that of asdeposited

crystalline films with similar structure. The hardest films have a single W-metallic phase

mixed with amorphous Si-N phase.

The Si content is determinant in the oxidation resistance: the higher the Si content the lower the oxidation

rate is. As an example, the weight gain reached by a coating without Si at 650ºC is similar to

the one shown by a high Si content film (>30at.%) at 1000ºC. The oxidation resistance is attributed

to either the formation of a continuous protective Si-rich layer or to the synergetic effect of a very

low oxide grain phase and a very high compactness of the oxide scale.

39


JUNE 26 MONDAY AFTERNOON

ETCHC-MoA-OR.10 MODIFICATIONS OF TRIBOLOGICAL BEHAVIOUR OF

STAINLESS STEELS BY DUPLEX TREATMENTS. R. J. Rodriguez, J.A. Garcia, R.

martinez, G. G. Fuentes. AIN. Centro de Ingeniería Avanzada de Superficies. 31191 Cordovilla,

Pamplona, Spain

Ordinary PVD coatings exhibites adequate properties from the point of view of hardness, friction or

wear coefficient to provide a solution good enough for many of the problems. However, they are 2 –

5 μm thick, a limit that can not be surpassed due to internal stresses that lead to crack formation and

delamination. In addition, soft substrates like stainless steels are not adequate to be coated by a hard

material (hardness beyond 15 GPa), because the plastic flow of the substrate induces the fracture of

the hard coating even at medium contact pressures.

DUPLEX treatments (ion nitriding + PVD coatings) have been proposed as a solution for the

treatment of metal alloys like, stainless steels, titanium alloys or, even, aluminium alloys, as well as

tool steels. Most of PVD industrial systems could be adapted to provide an ion nitriding treatment

prior to the PVD deposition process. Both treatments can be applied in the same chamber, without

breaking the high vacuum conditions to prevent contamination.

This papers reports the results obtained on on AISI 304 and 316 stainless steels by a DUPLEX

treatments: Ion nitriding + PVD coating. An adapted arc-evaporation PVD coater has been employed

to produce nitrided layers of 10 – 20 μm with different process parameters, by employing an original

nitriding process based on the AEGD configuration. The same equipment has been used to

subsequently deposit the PVD coatings.

GD-OES analysis and FE-SEM inspection have allowed to characterise the main features of

DUPLEX treatments in comparison with ordinary coatings. Changes in roughness, micro-hardness,

adhesion, friction and wear coeficcients have been measured. As an overall conclusion, both

DUPLEX treatments have shown improved properties and better behaviour.

KEYWORDS PVD, nitriding, duplex treatment, tribology.

38


JUNE 26 MONDAY AFTERNOON

ETCHC-MoA-OR.9 CHANGES DETECTED IN ECR-CVD AMORPHOUSAND NI-

TROGENATED AMORPHOUS CARBON FILMS BY INCREASING PLASMA ION ION

ENERGY. J.G. Buijnsters, M. Camero, L. Vázquez, C. Gómez-Aleixandre, J.M. Albella, Instituto

Ciencia de Materiales, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain

Hydrogenated amorphous carbon (a-C:H) and nitrogenated amorphous carbon (a-CN:H) thin films

may present interesting properties like high smoothness, low friction coefficient, high hardness and

high wear resistance which make them excellent candidates for different applications. a-C:H and a-

CN:H films have been grown from methane/argon and methane/nitrogen/argon gas mixtures respectively

by Electron Cyclotron Resonance Chemical Vapour Deposition (ECR-CVD). During the

deposition process, a negative DC bias voltage was applied to the substrate in order to obtain high

energy ions arriving at the growing surface. The effect of the ion energy on the structural, morphological

and mechanical properties of the films has been explored by multiple analysis techniques.

The obtained results clearly show a sharp change in the properties of the a-C:H and a-CN:H layers

from a threshold ion energy in the order of 100 eV for the production of hard, low-friction coatings.

For no bias application or bias voltages more positive than –100 V, cauliflower shaped and relatively

soft polymeric (nitrogenated) carbon films are formed. The change in the properties of the films deposited

in the two distinct deposition regimes has been associated with the new nanostructure of the

films detected by surface analysis techniques.

37


JUNE 26 MONDAY AFTERNOON

ETCHC--MoA-INV.2 NANOSTRUCTURED PVD COATINGS ON THE VERGE OF

INDUSTRIAL APPLICATIONS. Rafael J. Rodríguez, José-Antonio García, Gonzálo García and

Rosario Martínez. AIN. Centro de Ingeniería Avanzada de Superficies. 31191 Cordovilla – Pamplona,

SPAIN.

The search for new high performance coatings has experienced a relevant progress due to the recent

attention paid to the properties of nanostructured materials. In the last ten years a huge amount of results

have been published describing how nanostructured PVD coatings may exhibit excellent combinations

of different properties, including super- or ultra- hardness, extreme wear resistance, higher

toughness and corrosion resistance.

Most of these results have been achieved at laboratory scale. It seems that there is a real difficulty to

scale up these promising findings to exploitable industrial applications. By the way, this has been not

any obstacle for employing the mark “nano-“ in many commercial names of new coating introduced

in the market in the last five years.

This paper intends to make a review of most interesting strategies employed for the research groups:

nano-multilayers and nanocomposites approaches. A critical revision of the claimed new properties

is made, paying special attention to their possibilities of industrialization. Related problems like

techniques and standards to measure the coatings characteristics are also reviewed.

Keywords: PVD, multilayers, nanocomposites, industrial applications.

36


ETCHC SESSION

35


MONDAY AFTERNOON

34


JUNE 26 MONDAY MORNING

WS-18-MoM-OR.3 NEUTRAL PRESSURE MEASUREMENTS IN TJ-II PLASMAS.

F.L Tabarés, D. Tafalla and J.A. Ferreira. Laboratorio Nacional de Fusión por Confinamiento

Magnético, CIEMAT, Avda Complutense 22, Madrid

The density of neutral species in the periphery of a hot plasma, such as in those generated for Fusion

research, represents a net particle source, ideally in equilibrium with the recycling flux of particles

escaping the plasmas due to limited magnetic confinement. Its measurement in Fusion plasmas is of

crucial interest in particular when divertors are used for the control of the particle and power outflux,

and several concepts have been put forth for its recording (1). In limiter devices, however, its

measurement has always been rather problematic. This is mostly due to the difficulty in defining the

concept of pressure itself under such anomalous conditions, i.e., in the region between the hot plasma

and the walls, where strongly non-thermal equilibrium conditions prevail. Even so, the recording of

the manometer readings during the plasma production can provide very useful information about the

particle confinement and recycling. In the TJ-II stellarator (2), a set of manometers, including

Bayard-Alpert gauges and baratrons, is routinely used for the control of the particle fluxes injected

into the plasma. Recently, the direct reading of the pressure evolution during the plasma shot at regions

away from the gas injection ports has also become available. Neutral pressures values in the

order of 10 -5 -10 -4 mbar have been recorded, depending on plasma heating and wall recycling conditions.

In this work, the technique of measurement and the interpretation of the readings will be described.

The implications for the density control of the plasma and the possible improvements for future

analysis of the particle out-flux will be also discussed.

1. H.F. Dylla. J. Vac. Sci. Tech. 20 (1982) 119

2. F.L Tabarés, A. García, J. Botija, 45 Vacuum (1994) 1059

33


JUNE 26 MONDAY MORNING

WS-18-MoM-INV.2

Metrology

VACUUM STANDARDS AT CEM. C. Matilla. Spanish Centre of

In the next future CEM will have three different vacuum standards to cover all the vacuum range.

These standards are a dynamic expansion system, a static expansion system and a forced balance piston

gauge. The dynamic expansion system is based on the known orifice flow technique in which a

flowmeter is used to generate a known flow rate of gas in a vacuum chamber partitioned by an orifice

of calculated conductance. It has been working for some years but it has suffered several modifications

to make it more accurate. The forced piston balance is a recent acquisition. It is a pressure

standard designed to cover the range from less than 1 Pa to 15 kPa gauge and absolute pressures. The

instrument operates on the piston gauge principle in which the pressure on the piston is measured by

a forced balanced load cell. We were encouraged to acquire it by the good results obtained by other

metrology institutes. At the moment we are testing its performance and we are satisfied with its results.

The static expansion system is based on Boyle´s law with corrections. It is a project in collaboration

with EUITT (UPM), which has been founded by the R&D National Plan. This project will be

finished in 2008.

32


JUNE 26 MONDAY MORNING

WS-18-MoM-OR.2 NUMERICAL MODELING OF THE ION BEAM TRANSMIS-

SION EFFICIENCY FOR DESIGN OF THE VACUUM SYSTEM OF THE DC-60 CYCLO-

TRON. A.V. Tikhomirov, G.G. Gulbekian, B.N. Gikal. Flerov Laboratory of Nuclear Reactions,

Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow region, Russia.

The results of a numerical simulation of the transmission efficiency of ion beams in conditions of ion

recharge on the residual gas in the channel of the axial injection, in the DC-60 cyclotron vacuum

chamber, as well as in transport lines of accelerated beams are presented. The computer modeling

programs GENAP and VACLOS have been used. They have been developed and tested on the basis

of experiments on four cyclotrons of heavy ions of the Flerov Laboratory of Nuclear Reactions. They

also have collected an experience of vacuum systems’ design of a number of projects for both design

of new cyclotrons and their upgrade. The simulation programs estimate ion beam losses on the basis

of pressure distribution modeling in vacuum chambers of any arbitrary geometry and also on cross

sections calculation for a recharge of ions in exchange reactions by electrons with molecules of residual

gas in a wide range of energies and masses of ions being accelerated. The outcomes of modeling

have provided the determination of main parameters and technical requirements for the vacuum

system of the DC-60 cyclotron designed for the heavy ion and proton accelerator complex of the

University in Astana of the Republic of Kazakhstan

31


JUNE 26 MONDAY MORNING

WS-18-MoM-OR.1 MASS SPECTOMETRIC ANALYSIS OF COMPLEX GAS

MIXTURES BY USING A CRYOGENIC TRAP: APPLICATION TO H2:CH4:N2 PLAS-

MAS. Jose A. Ferreira and Francisco L. Tabarés. Laboratorio Nacional de Fusión por Confinamiento

Magnético, CIEMAT, Avda Complutense 22, Madrid

The interpretation of mass spectra from gas mixtures showing strong overlapping of the cracking

contributions from their constituents has been always challenging, and it is particularly problematic

in carbon film deposition plasmas, with strong contribution from several kinds of hydrocarbons. In

the present work we describe the use of a cryogenic trap, suitable for thermal desorption studies

above liquid nitrogen temperatures, for the discrimination of species with overlapping cracking patterns.

The cryogenic trap is a simplified model of that described by C. Leitao et al. [1]. A DC glow

discharge with a total pressure of 10 mtorr was produced in a mixture of H 2 :CH 4 :N 2 with 80, 10 and

10 percent respectively. These types of plasmas are of particular interest in fusion research in relation

to a new technique being developed for the mitigation of tritium trapping by codeposition in the

next step fusion reactor [2]. The complex reactions present in the plasma lead to the formation of

numerous stable species that are difficult to identify by mass spectrometry alone. Thus, for example,

the presence of N 2 and CH 4 prevents the use of 28, 29, 16, 15 mass peaks in the deconvolution of the

spectra. Some volatile compounds like acetylene, hydrogen cyanide, ethylene etc. [2] are produced in

this kind of glow, conveying important information about the reactive processes taking place in the

plasma. However, their cracking peaks are strongly masked by the main plasma species. Many of

these compounds can be readily condensed at the liquid nitrogen temperature, 78 K. Once exposed to

the plasma products, the cryogenic sample can be ramp-heated to desorb the volatile species, therefore

obtaining different mass peaks that evolve with the temperature ramp depending on the dew

point of the different species. The obtained data are then compared to previous studies in this type of

mixtures.

[1] Carlos M.M. Leitao et al. Vacuum, Vol 52 (1999) 23-26

[2] F. L. Tabarés, V. Rohde et al. Plasma Phys. Control. Fusion, Vol 46 (2004) B381-B395

30


JUNE 26 MONDAY MORNING

WS-18-MoM.INV.1 STANDARS AND CALIBRATIONS IN VACUUM TECHNOL-

OGY. Karl Jousten, Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.

The measurement and control of vacuum is an important condition for many industrial processes,

e.g. for the coating of glasses, of DVDs und CDs, as well as the production of hard disks, memory

chips and processors for computers. In the future it may be even possible that extreme ultraviolet

light (EUV) is used for lithography in the semiconductor industry which makes vacuum necessary

for the transport of the EUV light. The reflective mirrors will need very good vacuum conditions in

order to keep their reflectivity timely stable and to make the whole lithography process a commercial

success.

For most applications vacuum has turned into a full commodity in the past 20 years, where the buyer

has not to care about its functioning. In this scheme, traceable vacuum gauge calibrations and the establishing

of standards have become to play an important role.

Traceable vacuum gauge calibration means that the reading of a calibrated gauge can be traced to a

primary standard for vacuum pressures that ensures highest accuracy and the traceability to the

physical units of the SI. Primary standards are operated by the national metrological institutes.

In 1999 most of the states of the meter convention signed a mutual recognition arrangement, by

which calibration certificates of national metrological institutes are accepted in all these states when

some conditions are fulfilled, among them a quality management system as described in the ISO

standard 17025.

For the further dissemination of the vacuum pressure scale as well as the characterisation of vacuum

pump performance, ISO specifications and standards have been developed or are presently under development.

This talk will give a complete overview of the vacuum primary standards, the international system of

checking their validity, the scheme of the gauge calibrations down to the end user as well as making

notes on the accuracy and reliability of vacuum gauges. The international standardisation work for

vacuum technology will be described, also.

29


WS-18 SESSION

28


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-OR.8 STUDY OF THE DC-SPUTTERED Mo ON POLYMER SUB-

STRATE FOR FLEXIBLE CIGS SOLAR CELLS M. Andrés and M.T. Gutiérrez. Dep. of Energy,

CIEMAT. Avda. Complutense, 22. 28040 Madrid SPAIN.

For the last few years interest in flexible thin film solar cells has been growing for space power applications,

building integration and portable electronic. Thin film Copper Indium Gallium Selenide

(CIGS) has been established as a leading contender to these applications. In a recent publication different

approaches to flexible CIGS thin-film solar cells has been reviewed [1]. There are numerous

challenges in developing the technology for manufacturing flexible CIGS, the substitution of the

well-established soda-lime-glass substrate by a flexible alternative with drawbacks and without the

generation of new obstacles is not a minor problem. The substrate requirements for flexible CIGS solar

cells are related with a high thermal stability, a sufficient film adhesion and an adequate surface

morphology.

Molybdenum (Mo) has been used almost exclusively as a back contact material for CIGS-based

photovoltaics. Key requirements of the Mo-coated polyimide films for photovoltaic applications are

a high electrical conductivity, ohmic contact to CIGS, and high temperature stability in the presence

of selenium during CIGS absorber deposition.

The aim of the work has been to prepare Mo-coated glass and polyimide and to evaluate their performance

as flexible back contact for CIGS solar cells. The intrinsic stress, orientation, adhesion,

microstructure, reflectance and electrical resistance of dc-sputtered Mo films on glass and polymer

substrates has been studied as a function of deposition parameters.

Following Thorton and Hoffman [2-4], who comprehensively studies stress in sputtered metallic

coatings, we have investigated the effect of Ar gas pressure on the internal film stress in magnetron

sputtered Mo with particular emphasis on the problems that are encountered when relatively high

melting point Mo coatings, with low thermal expansion coefficient , are deposited on polyimide substrates

having relatively high thermal expansion coefficient. Substrate expansion due to heating during

deposition places a tensile stress on the coating which is sufficiently large to cause cracking. This

difficulty is overcome most effectively by depositing the coating under conditions that build a compressive

intrinsic stress into the coating.

[1] F. Kessler , D. Hermann and M. Powalla, Thin Solid Films 480-481 (2005) 491

[2] J.W. Hoffman, J. Vac. Sci. Technol. A 12(4) (1994), 953

[3] J.A. Thorton and D. W. Hoffman, Thin Solid Films, 171(1989) 5

[4] D. W. Hoffman and J.A. Thorton, J. Vac.Sci. Technol. 20 (1982) 355

27


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-OR.7 INFLUENCE OF THE YTTRIUM CONTENT ON THE ME-

CHANICAL PROPERTIES OF Y 2 O 3 -ZrO 2 THIN FILMS PREPARED BY EB – PVD. I. M.

Ochando. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones

Científicas. Cantoblanco, 28049 – Madrid, Spain. D. Cáceres. Departamento de Física, Universidad

Carlos III de Madrid, E-28911 Leganés, Spain. F. J. García-López. Centro Nacional de Aceleradores,

Parque Tecnológico Cartuja’93, 41092 – Sevilla, Spain. R. Escobar-Galindo, R. J. Jiménez-Rioboó

and C. Prieto. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones

Científicas. Cantoblanco, 28049 – Madrid, Spain.

Zirconium oxide is a widely used material because of its heat resistance, low thermal conductivity,

high refractive index and high transparency in the visible and near infrared region, very high chemical

inertness and high laser damage threshold. Due to these properties, its applications can be found

in very different aspects of technology. For instance, zirconia has been applied as thermal barrier

coating (TBC)], optical filters, laser mirrors], oxygen sensors], and solid oxide fuel cells].

TBC’s based on yttria stabilized zirconia (YSZ) films prepared by electron beam physical vapour

deposition (EB-PVD) are candidates for advanced thermal barrier coatings for the new generation of

land-based gas turbines because of the different obtained microstructure respect to other deposition

techniques. The low thermal conductivity magnitude for the films is mainly due to two factors: the

film microstructure and the intrinsic thermal conductivity value. For YSZ system, this second factor

is related with the oxygen defect structure which is induced when Zr 4+ ions are substituted with trivalent

Y 3+ ions giving rise to oxygen vacancies to compensate electrical charge.

Undoubtedly, mechanical properties are of significant importance for TBC and optical applications.

In this work, we present a nanoindentation characterization, where hardness and Young modulus

have been obtained for a set of (Y 2 O 3 ) x -(ZrO 2 ) 1-x thin films prepared by EB-PVD on Si(100) substrates,

in order to study the hardness dependence on the yttria content.

26


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-OR.6 A MINIMALIST SURFACE DECOMPOSITION METHOD AP-

PLIED TO STUDY THE SURFACE CONTROL OF THE Au POLYCRYSTALLINE CO-

LUMNAR FILM GROWTH. E. Rodríguez-Cañas *, and J. L. Sacedón. Instituto de Ciencia de

Materiales de Madrid (CSIC), 28049 Cantoblanco, Madrid, Spain. J. A. Aznárez. Instituto de Física

Aplicada (CSIC), Serrano 144, 28006 Madrid, Spain. A. I. Oliva. Cinvestav del IPN Unidad Mérida,

Dpto. de Física Aplicada, AP 73- Cordemex 97310 Mérida, Yucatán, Mexico

A method based in the minimalist decomposition of surface morphologies is proposed for the study

of surface protrusion terminated growth fronts. The method is applied to the STM morphology images

of Au films thermally evaporated on native SiOx/Si(100) for a wide range of Au thickness (60-

1800 nm). In this case the bulk film morphology corresponds to a columnar competitive growth, and

the growth front is composed of assembled paraboloidal meridian zones. The application of the

method allows the numerical synthesis of height distribution curves by the convolution of the statistical

parameters of the minimalist components. A complete set of statistical parameters, mean values

and fluctuations, and their scaling during the growth are obtained. The slope at the borders of

paraboloidal meridian zones are maintained near constant during the growth and appears as the controlling

growth parameter. In fact its high value and the slope distribution curves can be explained by

an out of equilibrium growth, controlled by steering and interface phenomena at border of the terraces

in addition of an effective Ehrlich-Schwoebel step-edge barrier. The scaling agrees with simulations

in which similar selected slopes are considered. One of the minimalist parameters is the fluctuation

of the columnar height at the film surface, allowing to establish its relation with the other surface

roughness parameters

25


JUNE 26 MONDAY MORNING

RIVA-TF.MoM-OR.5 LOW TEMPERATURE DEPOSITION OF TIB 2 ON X40

CRMOV 5 1 STEEL SUBSTRATE BY DC MAGNETRON SPUTTERING. A. Duarte 1,2 *, B.

Coelho 2 , M. Vila 2 , A.J.S. Fernandes 3 , F. Oliveira 2 , F.M. Costa 3 R.F. Silva 2 . 1 - Laboratório - F. Ramada,

Aços e Industrias, S.A., Apartado 10, 3880-909 Ovar, Portugal. e-mail:

paulo.duarte@ramada.pt 2 - CICECO - Dept. of Ceramics & Glass Engineering, University of Aveiro,

3810-193 Aveiro- Portugal 3 - Dept. of Physics, University of Aveiro, 3810-193 Aveiro- Portugal

Titanium diboride (TiB 2 ) films are being investigated due to their promising uses not only in electronic

devices but also for mechanical purposes. Its excellent corrosion resistance and chemical stability,

as well as high hardness and wear resistance makes TiB 2 particularly suitable for aluminium

processing (e.g. extrusion, die-casting and machining). The major concern about protective coatings

is lack of adhesion to the substrate arising from the high residual stresses developed during film

deposition.

In the present work TiB 2 coatings were produced by non-reactive magnetron sputtering from a TiB 2

target on Orvar Supreme tool steel substrate (also know as AISI H13 premium or X40 CrMoV 5 1).

Two different substrate types were used, similar to those frequently found on the aluminium injection

industry: quenched and tempered/nitrided. The deposition parameters, namely the target/substrate

distance, emission and bias currents, were varied in order to obtain adhered and well

structured films, suiting the substrates composition and microstructure. The coatings were characterized

by X-Ray diffraction, Scanning electron microscopy/EDS, Scratch test and AFM. The results

obtained show that TiB 2 can be grown on the steel substrate at low temperature with high deposition

rate keeping some crystallinity degree. Depending on the experimental parameters it is possible to

coat hot work tool steel with adherent TiB 2 thin films by DC sputtering.

*corresponding author

24


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-OR.4 Ta 2 O 5 THIN FILMS PREPARED BY EVAPORATION AND

IBAD METHODS: CHARACTERIZATION AND WETTING BEHAVIOUR UNDER UV

IRRADIATION. V. Rico, J.P. Espinós, F. Yubero, F. Frutos*, A.R. González-Elipe. Instituto de

Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla). Avda. Américo Vespucio s/n. 41092 Sevilla

(Spain). *Dpto. Física Aplicada I, ETS Ingeniería Informática. Avda. Reina Mercedes s/n. 41012

Sevilla (Spain)

Ta 2 O 5 thin films have been prepared by evaporation from a tantalum oxide precursor and by assisting

the growth of the films by oxygen and nitrogen ion bombardment (IBAD). The obtained thin films

depict different microstructures and optical and dielectric properties. In general, the films prepared

by evaporation have lower refraction indices that those prepared by IBAD. In this case a clear correlation

exists between the ion current and energy and the properties of the films. The trend of dielectric

properties of these thin films agrees with that defined by their optical properties. They also agree

with the microstructrue of the films as determined by SEM. A particular type of films was found

when prepared by evaporation under grazing conditions. These films depict a columnar microstructure

with oblique columns and an extremely high porosity. Refraction indices ranging from 1.7 to 1.2

have been obtained for these thin films.

Another interesting property of these thin films refers to its wetting behaviour under UV light. In literature

there are many papers dealing with the conversion of the TiO 2 surface from partially hydrophobic

into fully hydrophilic by UV irradiation. In this work we also show that Ta 2 O 5 thin films present

a similar behaviour changing from hydrophobic into hydrophilic by illumination. A careful

study of this type of transformation is being carried out as a function of the microstructural and structural

properties of the films. Doping of Ta 2 O 5 thin films with foreign cations and with nitrogen has

revealed to be an effective way to induce a partial change in wetting angle by using visible light for

the illumination.

23


JUNE 26 MONDAY MORNING

RIV-TF-MoM-OR.3 EPITAXIAL MATCHING OF SMALL METALLIC NANO-

CLUSTERS IN LARGE-MISFIT SYSTEMS. J.C. Jiménez-Sáez. Departamento de Física y

Química Aplicadas a la Técnica Aeronáutica, E.U.I.T. Aeronáutica, Universidad Politécnica de Madrid

(UPM), E-28040 Madrid, Spain. E-mail: jc.jimenez@upm.es. A.M.C. Pérez-Martín and J.J.

Jiménez-Rodríguez. Departamento de Electricidad y Electrónica, Facultad de Ciencias Físicas, Universidad

Complutense, E-28040 Madrid, Spain.

The deposition at low energies of Cu and Au nanoclusters on the Au(001) and Cu(001) substrates respectively

is studied by constant temperature molecular-dynamics simulations. Clusters have icosahedral

or Wulff symmetries. Their number of atoms ranges between 13 and 1289. Atomic interactions

are mimicked by a many-body potential based on the tight-binding model. Deposition energy is

of the order of meV/atom and the temperature was 300 K. We have investigated the equilibrium

structure of deposited metallic clusters. The influence of the cluster size and of its shape in the lowenergy

limit on the epitaxial matching has been analyzed. We have taken into account the large lattice

misfit between the cluster and the substrate (12.8% for Cu/Au(001) and 11.35% for

Au/Cu(001)). Previous results show that in cases without misfit the epitaxial growth depends on the

size of the clusters and on the temperature as well. Besides in previous works, we have found a different

elastic behaviour in large clusters when deposition energy is lower or higher than 30

meV/atom. These differences can also induce variations in the epitaxial alignment between cluster

and substrate. The possible matching between both structures has been studied by the common

neighbour analysis, CNA, which classifies the types of bond; by both the structure factor and an epitaxy

factor which asses the degree of adaptation of both lattices; and finally, by a grain analysis

which allows to find out if the deposited-cluster lattice imitates the substrate lattice. Structural properties

of the interface (coherent, semicoherent or incoherent), in addition to the bond distances as a

function of the distance to the interface have been also investigated.

22


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-OR.2 STRAIN ANALYSIS OF PHOTOCATALYTIC TiO 2 THIN

FILMS ON POLYMER SUBSTRATES. C.J. Tavares 1 , S.M. Marques 1 , V. Teixeira 1 , J.O. Carneiro

1 , A.J. Fernandes 2 , E. Alves 3 , A.R. Ramos 3 . 1 Departamento de Física, Universidade do Minho,

4800-058 Guimarães, Portugal. 2 Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro,

Portugal.

3 Instituto Tecnológico e Nuclear, EN 10, 2686-953 Sacavém, Portugal.

ctavares@fisica.uminho.pt

Titanium dioxide (titania) is a well known photocatalyst used in the semiconductor industry due its

efficiency in dissociating pollutant organic compounds. Enhancing the photocatalytic efficiency of

this material has become a major concern for the authors, bearing in mind industrial applications for

general purpose plastics. On an industrial environment, handling of these films often may cause degradation

of the coating, hence the vital importance of also enhancing the mechanical properties. TiO 2

thin films have been deposited by unbalanced reactive magnetron sputtering from a high purity Ti

target in an Ar/O 2 atmosphere, at room temperature, on polymer sheets. X-ray diffraction experiments

revealed for a wide range of deposition parameters that the as-deposited titania thin films are

amorphous. The photocatalytic behaviour of the titania coatings was determined by combined ultraviolet

irradiation and absorption measurements. The observed photo-decomposition of the aqueous

solution (organic pollutant) was measured in the UV/Vis spectrum by the decrease of the maximum

absorbance with irradiation time. Analysis of the absorption data allowed us to obtain the decrease in

concentration as a function of time to be observed. In order to assess the mechanical behaviour of the

as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile

testing machine. As the system is stretched, cracks transverse to the loading direction developed in

the film. The number of cracks increased as the applied strain increased, and the relation between the

measured crack density and the applied strain has been used to characterize the film strength and relate

it with the film photocatalytic efficiency.

21


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-OR.1 DETERMINATION OF THE HYDROGEN CONTENT IN

DIAMOND-LIKE CARBON AND POLYMERIC THIN FILMS BY REFLECTION ELEC-

TRON ENERGY LOSS SPECTROSCOPY. J. Rico, F. Yubero, J.P. Espinós, J. Cotrino, and

A.R. González-Elipe. ICMSE (CSIC-USE) Amério Vespucio s/n, E-41092 Sevilla, Spain D. Garg.

Air Products and Chemicals, Inc. 7201 Hamilton Boulevard, Allentown, PA 18195-1501, USA

A new non-destructive method to determine hydrogen content in diamond-like carbon and polymeric

thin film materials is developed. The method relies on quantification of the intensity of elastic peak

stemming from the backscattering of electrons with the hydrogen atoms present in the samples as

measured by reflection electron energy loss spectroscopy. Quantitative analysis of the hydrogen

content at the surface of diamond like carbon thin films is achieved by using phenomenological sensitivity

factors of hydrogen against the other atoms with reference to polymeric samples. The validity

of the method is checked with elastic recoil detection measurements. A comparison is also made

with data provided by infrared spectroscopy analysis of the same samples. We estimate that the error

bar in the determination of hydrogen content in the samples is around 20% of the total hydrogen

content.

20


JUNE 26 MONDAY MORNING

RIVA-TF-MoM-INV.1THIN FILM STACKS FOR SPINTRONIC DEVICES: PREPARATION

AND CHARACTERIZATION, P.P.Freitas, S.Freitas and R.Ferreira. INESC MN, Lisbon, Portugal

and Physics Department, Instituto Superior Tecnico, Lisbon, Portugal

Physical Vapour Deposition (PVD) and Ion Beam Deposition (IBD) tools are described as used for the

preparation of spintronic device stacks ( hard disk read heads-spin valve and tunnel junction,

MRAMS, sensor stacks). These tools allow the uniform deposition of multilayered stacks over 8” wafers,

where each individual layer has thickneses down to 1nm. The formation of nm thick AlOx and

MgO barriers, critical to the formation of state of the art tunnel barriers is revised. For device patterning,

both ion-milling and reactive ion etching techniques are used, the latter becoming necessary for

device features below 100nm. The complexity of the magnetic stacks poses several challenges for reactive

etching techniques. Finally, spintronic device examples will be given, starting with magnetic

tunel junction read heads for magnetic data storage at densities beyond 100Gbit/in2, followed by

MRAMS, and different types of field sensors for position, current, and biomedical imaging applications.

19


RIVA-TF SESSION

18


JUNE 26 MONDAY MORNING

ETCHC-MoM-OR.8 BORON IMPLANTATION EFFECTS IN CdDS THIN FILMS

GROWN BY CHEMICAL SYNTHESIS. K. L. Narayanan, M. Yamaguchi, Toyota Technological

Institute, 2-12 Hisakata, Tempaku, Nagoya-468 8511, Japan.. R. Lozada-Morales 1 , O. Portillo-

Moreno 2 . Benemérita Universidad Autónoma de Puebla. 1 Departmento de Optoelectrónica, Facultad

de Ciencias Físico-Matemáticas. 2 Facultad de Ciencias Químicas. Puebla, México.O. Zelaya-Angel.

Departamento de Física. Centro de Investigación y de Estudios Avanzados del IPN. P.O.Box 14-740,

México 07360 D.F.

We prepared CdS thin films on ITO/glass substrates using a chemical bath, which were boronimplanted

employing 200 keV beams doses of B + ions in the range 1.0 x 10 15 – 1.0 x 10 16 ions/cm 2 .

The B-doping was successfully carried out, as was proved by the excess of carrier density introduced

in the range 0.8 x 10 18 – 5.4 x 10 18 cm -3 , which was calculated from thermopower measurements that

we made. The Raman spectroscopy results support the assumption that doubly ionized B + (B 3+ ) enter

into the CdS lattice occupying Cd 2+ sites, which create shallow donor levels in the forbidden energy

band gap, in a similar way that it happens with In 3+ ions in CdS.

17


JUNE 26 MONDAY MORNING

ETCHC-MoM-OR.7 TUNGSTEN OXIDE WITH DIFERENT OXYGEN CON-TENT:

SLIDING PROPERTIES. T. Polcar, N.M.G. Parreira and A. Cavaleiro a * ICEMS – Grupo de

Materiais e Engenharia de Superfícies, Faculdade de Ciências e Tecnologia da Universidade de

Coimbra – Pólo II, 3030-201 Coimbra, Portugal. * To whom all correspondence should be addressed

(albano.cavaleiro@dem.uc.pt)

Tungsten oxides were studied in the past due to their electro-optical properties (e.g. exhibit electrochromic

behaviour) and, more recently, due to their applications in gas sensor devices. These studies

were particularly focus on the stoichiometric compound WO 3 or WO 3-x (x = 0–1) prepared by different

method. However, it is difficult to prepare tungsten oxide with low oxygen content by equilibrium

process, since the solubility of oxygen in tungsten in such conditions is very low. Therefore, the

non-equilibrium processes must be used being reactive sputtering the most versatile.

The sliding properties of tungsten oxide coatings are not well known. Tungsten trioxide studied by

Lugscheider et al. showed good tribological properties. It is supposed, that sub-stoichiometric tungsten

trioxide can act as a solid lubricant due to presence of the so-called “Magneli” phases. These

phases exhibit a wide range of structures, which leads to the crystallographic shear planes with reduced

binding strength.

In this study, we prepared tungsten oxide by reactive magnetron sputtering with oxygen contents of

13 and 75 at.%. Detailed analyses of the XRD patterns of the former W–O coating showed the b.c.c.

α-W phase. However, the position of the diffraction peak moved to the lower diffraction angles

compared to α-W phase of pure tungsten. This means that oxygen is allocated at the interstitial positions

in the lattice, which leads to higher lattice parameters and induces compressive residual stress.

Concerning the W 25 O 75 coating, the diffraction peaks of XRD pattern suggest a nanocrystalline

structure. At the moment, it is difficult to state that it corresponds to the WO 3 monoclinic (the equilibrium

structure), since the ICDD patterns ofW 20 O 58 , W 5 O 14 , WO 2.90 , and others forms of WO 3 (cubic,

orthorhombic, triclinic) also have diffraction peaks in the same region as the WO 3 monoclinic

phase.

The hardness and Young’s modulus were evaluated by depth sensing indentation. W 87 O 13 and

W 25 O 75 coatings exhibited hardness of 26 GPa (similar to that of pure tungsten) and 7 GPa, respectively.

The coatings displayed a relatively low adhesion (critical load Lc


JUNE 26 MONDAY MORNING

ETCHC-MoM-OR.6 SPUTTERING OF NITRIDES BY LOW-ENERGY IONS OF

DIFFERENT MASSES . S.S. Elovikov, A.S. Mosunov, J. C. Colligon*, Yu.A.Ryzhov,

I.I.Shkarban, V.E.Yurasova, E.Yu.Zykova. Physics Faculty, Moscow State University, Moscow,

119899, Russia. *Manchester Metropolitan University. John Dalton Extension. Manchester M1 5GD,

England, UK

The results of calculations of mass dependence of sputtering yields for nitrides with various ratios

between masses of their components, i.e. BN, AlN, and GaN, are presented. The effect of masses of

bombarding ions with energy from 200 to 2000 eV on sputtering yields, mean energies and energy

spectra of sputtered particles, depths of sputtering origin and number of generations of emitted atoms

for nitrides was investigated and discussed.

Study of sputtering of these nitrides is of interest both for physics of interaction between atomic particles

and solids and from practical viewpoints. BN is an important constructional material due to a

set of useful physical and chemical properties: high hardness and electric strength, good heat conduction,

thermal and chemical stability. AlN is known for strength, elasticity, good heat conduction, and

dielectric strength, and is used in acoustic devices and as a coating in spacecraft components. GaN is

used in light-emitting diodes and other electronic devices. In many of applications, surfaces of nitrides

are subject to various kinds of irradiation, which often leads to degradation of their properties.

Therefore, it is important to know the resistance of these nitrides to the low-energy ion irradiation.

We have used the MD simulation with a mobile single-crystal block of atoms. Polycrystal was simulated

by rotation of single-crystal block through arbitrary angles for every impinging ion. Inelastic

loses were taken into account. Thermal vibrations were considered as uncorrelated. Equations of motion

were integrated using predictor-corrector modified scheme. The interaction potential:

U(r)=a bm (1+a b /r)exp(-r/b),where a bm = 52(Z 1 Z 2 ) 3/4 , a b = (Z 1 Z 2 ) 1/4 /52, b = 0.219Å, Z 1 and Z 2 are the

atomic numbers of the impinging ion and the target atom, respectively. Binding energy E b of surface

atoms was estimated from value of cohesion energy per a bond between atoms in compounds and

was corrected using the experimental results. E b value, thus selected, is: 8.1, 6.8, and 5.4 eV for BN,

AlN, and GaN, respectively.

It was shown that the sputtering yields Y of BN, AlN, and GaN as functions of mass m 1 of normally

incident low-energy ions have a nonmonotonic character with a maximum for small m 1 . For targets

with medium mass of atoms (AlN, GaN), the Y(m 1 ) maximum is observed at m 2 /m 1 = 2 (where m 2 is

the mean atomic mass for compound). In the case of the light-target sputtering (BN), the Y(m 1 )

maximum is at m 2 /m 1 = 1. With increasing E 0 , the Y(m 1 ) maximum is shifted towards heavier masses

and then disappears.

Mean energies Ē 1 of particles sputtered by low-energy ions from AlN and GaN depend nonmonotonically

on m 1 with a maximum at the same values of m 1 as for Y(m 1 ). In BN, Ē 1 has maximum

for the lightest ions.

Energy spectra of a light component of nitrides, which give the main input to sputtering, differ qualitatively

for sputtering by low-energy ions of large and small masses. In the last case, the spectra have

longer high-energy tail and broader maximum of distribution that indicates more favorable conditions

of particle emission with higher energy.

Depths of origin x 0 of sputtered atoms for GaN and AlN increase with decreasing m 1 , particularly

sharp for small m 1 . For greater ion masses, at E 0 = 200 eV, the curves x 0 (m 1 ) reach a constant value at

x 0 ∼ 4 Å for AlN and GaN and slowly grow with m 1 for BN.

Distribution of the sputtering yield over the number of generations of emitted atoms differs significantly

for targets with light and with heavy masses of atoms. So, for BN, these are the tertiary recoils

that give the major contribution to sputtering. In the case of AlN and GaN, the sputtered atoms belong

to primary recoils at lower E 0 and to secondary recoils at higher E 0 .

A special feature of nitride sputtering is that the Y(m 1 ) curves reach saturation for lower values of E 0

than in the case of equivalent single-element target, with atomic mass equal to the mean of the

masses of the two components of the binary compound. This early saturation is caused by the presence

of the lighter component (i.e. N) in nitrides.

We would like to thank the Russian Foundation for Basic Research (grants 05-02-17227 and 05-02-

17870), and INTAS (grant 03-53-5607) for their support.

15


JUNE 26 MONDAY MORNING

ETCHC-MoM-INV.1 NANOCOMPOSITE HARD COATINGS AS INTERFACE DO-

MINATED MATERIALS. Jörg Patscheider, EMPA, Materials Science and Technology. Überlandstr.

129. CH-8600 Dübendorf, Switzerland. e-mail: joerg.patscheider@empa.ch

The introduction of ternary metal nitrides, leading to the coating materials with highly improved

properties, also brought about the discovery of nanocomposite coatings with increased hardness.

Such nanostructured coatings proved successful in promoting hardness, oxidation resistance, improved

wear behavior and other properties relevant for protective coatings. Examples for these materials

are TiN/Si 3 N 4 and TiC/a-C:H. Most nanocomposite hard coatings with well-separated phases

show typically a maximum of the hardness, which can range from 30 GPa to reported values exceeding

60 GPa, as the composition is changed from the pure polycrystalline phase (no amorphous component)

to compositions dominated by the amorphous phase. At the hardness maximum the domain

size of the nanocrystalline phase is below 10 nm and the average thickness of the amorphous layer

separating the nanocrystals, amounts to only one to two atomic bond lengths. The grain size at hardness

maximum for nanocomposites is the same as the single layer thickness in nanomultilayers at the

hardness maximum, suggesting similar hardening mechanisms in the two materials classes. contrast

to multilayers with its sequential deposition of individual layers, nanocomposites are prepared by

codeposition of the involved phases by ion-assisted processes such as unbalanced magnetron PVD,

arc-PVD and PACVD. The quality of the amorphous phase in terms of structural perfection and

thickness is of decisive influence for the performance of the coatings. ). It can be shown that the

chemical nature of the interfaces in TiN/SiN x , despite their inertness, governs the hardness. In some

cases the amorphous phase can act as diffusion barrier (Si 3 N 4 ) for improved thermal stability or as a

solid lubricant (a-C or a-C:H). The amorphous phases in nanocomposites thus cause, apart from the

enhanced hardness, additional effects that are beneficial for their performance.

14


JUNE 26 MONDAY MORNING

ETCHC-MoM-OR.5 OES TIME-RESOLVED CHARACTERIZATION OF THE

DEPOSITION OF MULTILAYERED COATINGS. J. Romero, A. Lousa. Departamento de

Física Aplicada y Optica, Universidad de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Catalunya,

Spain.

Multilayered structures with nanometric period and manocomposites materials are probably the most

promising alternatives to improve the properties of conventional coatings used for mechanical applications.

Multilayered structures are generally formed by alternatively piling two materials in a periodic

sequence ABABAB….., with a period Λ. Most of the multilayered structures referred in the literature

present mechanical properties that surpass those of their individual materials: increase of

hardness, elastic limit and toughness, and reduction of internal stresses.

We have developed a process for the deposition of multilayered structures by r.f. magnetron sputtering

in a continuous process. A single cathode with a metallic target (Cr) is used, and the alternate

deposition of two materials is achieved by periodically alternating the working gas composition. In

this way, the deposition of metal/nitride, metal/carbide and nitride/carbide multilayers can be

achieved just switching the gas composition between pure Ar and an Ar+N 2 , pure Ar and an

Ar+CH 4 , and Ar+N 2 mixture and Ar+CH 4 respectively.

Cr/CrN multilayered coatings with bilayer periods (Λ) between 120 and 2 nm were deposited by r.f.

magnetron sputtering (13.56 MHz) on Si wafers. The coatings were deposited by reactive sputtering

from a 3-in. diameter pure Cr target (99.99% purity) with a r.f. input power of 100 W and a targetsubstrate

distance of 5 cm. Two independent mass-flow meters controlled each gas flux (Ar and N 2 )

during deposition. Chromium thin films were deposited at 1.0 Pa pure Ar pressure, while chromium

nitride films were produced in Ar–N2 reactive mixtures where the total working pressure was 1.2 Pa

and the nitrogen partial pressure was 0.2 Pa. The Cr/CrN multilayers were deposited alternating both

experimental conditions. Cr and CrN growth rates were 0.8 and 0.6 μm/h, respectively; slow enough

to be able to produce multilayers in the nanometric range

Two nitrogen-related optical signals from plasma de excitation (N 0 2 = 337.1 nm and N + 2 = 391.4 nm,

were found to be the most easily monitored to appreciate changes in N 2 chamber presence. These

two well-defined nitrogen optical emission lines were measured in a time-resolved way during multilayer

deposition in order to monitor nitrogen in chamber residence time responses to the cyclic

switches in its flow.

Exponential time responses were found for cyclic switches, with relaxation times of 1.1 s for the N 2

switch off and 0.9 s for the switch on. These times are less than 4% of the deposition time corresponding

to a bilayer for bilayer periods down to 6-9 nm. Hence, for the multilayers with bilayer

thicknesses higher than 9 nm a well defined multilayer structure is expected, while for values lower

than 6 nm an increasing influence of interlayers and materials mixing is more probable to occur.

The multilayer structure was confirmed by TEM and LA-XRD measurements for bilayer periods

higher than 6 nm, what confirms the in-situ predictions of our OES measurements. The highest hardness

of the coatings set, 28 GPa, was obtained for the coating with the theoretic thinnest bilayer period

(Λ=2.1 nm). This maximum hardness was more than 100% higher than the expected value from

the rule-of-mixtures applied to CrN and Cr coatings

In summary, time-resolved OES plasma measurements are a useful tool to monitoring in-situ the

formation of well defined multilayer structures in a continuous process, with multilayer periods

down to a few nanometres.

13


JUNE 26 MONDAY MORNING

ETCHC.MoM.-OR.4 TRIBO-MECHANICAL PROPERTIES OF CrAlN COATINGS

DOPED WITH YTTRIUM AND ZIRCONIUM. M. Brizuela, D. González, A. García-Luis, P.

Corengia. Fundación INASMET-Tecnalia, Paseo de Mikeletegi 2, 20009 San Sebastián, Spain

The aim of this work is to study the influence of doping with Y and Zr on the mechanical and tribological

behaviour of CrAlN coatings.

CrAlN coatings doped with Y and Zr were prepared on high-speed steel (AISI M2) and Si (100) substrates

by d.c. magnetron sputtering using a commercial equipment (CemeCon® CC800/8) provided

of four targets, two of chromium, one of aluminium, and one of the doping material (yttrium or zirconium)

in a mixture of argon and nitrogen. The influence of different deposition parameters (e.g.:

Ar/N 2 ratio, temperature, doping target power,) on the chemical, mechanical and tribological properties

was analysed.

The mechanical properties of the films was evaluated with a Fischerscope H100 dynamic microprobe

apparatus using a conventional Vickers indenter at loads up to a maximum of 10 mN, to minimise

the influence of the underlying base material. Adhesion testing was carried out with a conventional

VTT scratch test on films deposited on polished M2 steel samples. Critical loads for adhesion were

calculated by optical observation at the first cohesive or adhesive failure of the coating. The friction

and wear tests have been performed in a pin-on-disk apparatus against different counterpart materials

(AISI 52100 steel and Ti6Al4V alloy). Friction coefficients were continuously recorded during the

tests. Wear volume and surface morphology were evaluated on worn areas of coated discs and balls

after testing by means of non-contact laser surface profilometry, scanning electron microscopy

(SEM) and energy dispersive spectroscopy (EDS). Chemical and microstructural properties have

been also investigated by EDS and SEM.

The results show great differences when using different doping elements and deposition conditions.

The role of the amount and type of doping element has been investigated. Hardness values up to 40

GPa have been found in the case of CrAlN coatings doped with yttrium under certain deposition

conditions. The tribological behaviour has also been studied and correlated with the chemical composition

and mechanical properties.

12


JUNE 26 MONDAY MORNING

ETCHC-MoM-OR.3 STUDY OF HYDROGEN AND OXYGEN UPTAKE IN SMART

OPTICAL WINDOWS BASED ON YPd AND MgNiPd THIN FILMS BY GDOES. E. Matveeva,

E.Rayon. Centro MTM, Universidad Politécnica de Valencia, Cami de Vera s/n, E-46022

Valencia Spain. R. Escobar Galindo, J.M. Albella. Departamento Física en Ingeniería de Superficies,

Instituto Ciencia de Materiales, Cantoblanco, E-28049 Madrid, Spain.

The use of smart optical windows based on YPd and MgNiPd thin coatings on transparent glass, has

been extensively studied in the last 15 years due to the possibilities of switching the optical and electrical

properties in a reversible and controlled way. The key of the switching process is based on the

absorption of hydrogen by the reflective metal, converting it to a transparent and semiconductor

metal hydride. In our case, the control of the hydration is carried out by an electrochemical process

in which the hydrogen ions are absorbed onto the metallic cathode. During the anodic discharge, the

hydrogen is released from the metal hydride towards the alkali electrolyte where other reactions may

take place (i.e. metal oxidation). These complex processes are localised in-depth the film thickness

(approximately 200 nm) and at the interfaces. Incontrollable oxidation of the active films during anodic

discharge depending on the position in the film of the oxide formed can block the hydrogen diffusion

process and reduce hydrogenation limiting the lifetime of the devices. Therefore, it is crucial

to have a detailed knowledge of the mechanisms of hydrogen and oxygen uptake and release in the

films. Most of the previous studies has been done by X-ray and infrared characterisation techniques,

but they do not provide depth profile information.

As an alternative, in this work, we have made use of the high elemental sensitivity and nanometre

depth resolution of radiofrequency Glow Discharge Optical Emission Spectroscopy (rf-GDOES) to

study the depth profiles of the elements present in the films. In particular, the hydrogen and oxygen

uptake and release was followed in samples subjected to different charge and discharge processes.

GDOES measurements were performed after each electrochemical experiment (charging and discharging),

whose kinetics was recorded,. The most representative observations of the GDOES results

were: i) The resolution of the layer structure of the film (5 nm Pd/metal layer/glass), ii) the detection

and monitoring of hydrogen migration in and out of the film during loading and release cycles and

iii) the revelation of the enhanced oxidation of the film after an anodic discharge. The relation of

these observations with the performance of the devices will be further discussed in this paper.

11


JUNE 26 MONDAY MORNING

ETCHC-MoM-OR.2 COMPUTER DESIGN OF OPTICAL COATINGS IN SYSTEMS

WITH CONTINUOUSLY VARYING REFRACTIVE INDEX. J.F. Trigo. Departamento de

Energía, CIEMAT, Avda. Complutense 22, E-28040 Madrid, Spain. I. Preda, S. Palacín, A. Gutiérrez

and L. Soriano. Departamento de Física Aplicada C-XII, Universidad Autónoma de Madrid, Cantoblanco

E-28049 Madrid, Spain

A simple computerized method for the calculation and refinement of a multilayer discrete optical design

has been used to test the accuracy and stability of the given solution with continuously varying

refractive index systems as compared with usual high-low (HL) bilayer systems.

Motivated for the study of nanostructured mixed materials, which results in a controlled variation of

the index of refraction, a code for multilayer Reflectance-Transmittance calculation has been modified

to treat the problem of continuously varying refractive index. An example of sinusoidal variation

has been studied and compared with discrete HL multilayer to produce a step filter. Also the stability

of the filter Transmittance against a random dispersion of the layers thickness has been compared.

The conclusion of the comparison was that the bilayered model was better in producing sharp step

filters but this performance was rapidly destroyed by a random dispersion up to a 20% of the layers

thickness whereas the sinusoidal continuous variation of the refractive index filter remained stable in

the same condition. This indicates that the design calculated for these continuous systems would be

more easily produced and reproduced in batch industrial processes.

On the other hand, the calculation and refinement of the continuous optical coating is much more

time consuming with our method so considerable effort has been done to improve the code in this

sense.

10


JUNE 26 MONDAY MORNING

ETCHC--MoM-OR.1 ROOM TEMPERATURE PL CHARACTERIZATION OF MI-

CRO- AND NANOCRYSTALLINE DIAMOND GROWN BY MPCVD FROM AR/H 2 /CH 4

MIXTURES M.A. Neto. CICECO Dept. of Ceramics & Glass Engineering, University of Aveiro,

Portugal. A.J.S. Fernandes. Dept. of Physics, University of Aveiro, Portugal. R.F. Silva. CICECO-

Dept. of Ceramics & Glass Engineering, University of Aveiro, Portugal. F.M. Costa. Dept. of Physics,

University of Aveiro, Portugal

Since the first successful efforts to synthesize diamond by chemical vapour deposition (CVD) in the

mid-eighties, many technical and scientific improvements have been achieved. Growth rates, quality

grade and size up-scaling put CVD diamond into the industrial reality for mechanical and thermal

applications, among others. Until recently, most of the available products were based on microcrystalline

CVD diamond (MCD) thick films for brazing or, alternatively, directly coated thin films on

tool substrates. Lately, nanocrystalline diamond (NCD) emerged as an alternative to the microcrystalline

material for some applications, mainly due to its enhanced smoothness and electronic properties.

Structurally, NCD is composed by small (2-100nm) crystallites frequently surrounded by a nondiamond

carbon matrix, resulting in a non-columnar growth. In opposition, MCD crystals grow in a

columnar structure according to the Van der Drift model with much lower grain boundary densities.

In this work, a photoluminescence (PL) study at room temperature was accomplished as a complement

to well established structural and morphological characterization techniques such as µ-Raman,

FTIR, XRD, XPS or SEM. Considering the wide electronic band gap of pure diamond (5.45eV), the

near UV excitation (325nm) from an HeCd laser source was selected. The observed NCD and MCD

samples were obtained by microwave plasma (MPCVD) from hydrogen poor Ar/H 2 /CH 4 mixtures. A

broad violet band dominates the PL spectra of both sample types, evidencing however a stress related

wavelength shift between them. The well known 1.681 eV peak related to the Si-vacancy color

centre is much more pronounced in the MCD samples, showing that silicon is incorporated in the

diamond lattice. In the case of NCD, the absence of the above mentioned peak suggests that Si is

probably trapped by the amorphous carbon phases at the grain boundaries. The samples were further

structurally and morphologically characterized by micro Raman spectroscopy, XRD and SEM.

9


ETCHC SESSION

8


PARALLEL SESSIONS

7


JUNE 26 MONDAY MORNING

MoM-Pl.1 QUALITY VACUUM MEASUREMENTS FOR PROCESS APPLICATIONS.

Charles R. Tilford, Independent Consultant, Gaithersburg, MD USA, CharlesTilford@Verizon.net

Vacuum technology is a rapidly maturing field with many industrial applications. This does not

mean an end to vacuum science investigations and technical development. However, it does mean

an increasing focus on the needs of large-scale processes, whether they are producing energetic particles

or consumer products. In addition, more of a focus on quality—fitness for purpose—whether

the vacuum contribution is hardware, measurements, or techniques. This process is already underway—witness

the change in vacuum equipment to meet the particular needs of the semiconductor

processing industry. But much more needs to be done and the vacuum community will be increasingly

called upon to apply their expertise outside of their own field of interest. There are many ways

of doing this, training courses and documentary standards for example. But there are times when it

is most useful for the vacuum specialist to directly collaborate with equipment manufacturers and

users of vacuum-technology. Because of the large variety of applications, and different backgrounds

of the users, this process can be difficult. But the benefits of such collaborations can be very great,

and such collaborations are already quite common in the vacuum equipment area. With the growing

complexity of vacuum processes and the importance of measurements for process control, it is probable

that there will more instances where the specialized knowledge and experience of vacuum

measurement specialists will be a welcome addition.

Direct participation in problem solving outside of their own field will be a new experience for some

vacuum measurement experts. But this is just the latest step in the evolution of vacuum measurements

and standards. This field started with the need to measure ever-lower pressures. Accuracy, to

the extent that it was ever considered, generally was with respect to a local reference—the “magic”

reading that produced an acceptable product, or agreement with a “standard” gauge. With the

growth of global trade and manufacturing this is no longer acceptable and vacuum measurements

must now be established with respect to the internationally accepted measurement system (the SI).

A great deal of progress has been made in establishing primary vacuum standards and calibration

systems, and ensuring international compatibility. But while proper calibration of an instrument with

respect to the SI is necessary, it is not sufficient to ensure that quality measurements are available for

the end use. It is also necessary that the calibrated instrument be stable, environmental influences

are understood and properly accounted for, the end user is able to properly operate the instrument,

and the entire process is affordable. Vacuum measurements are also especially susceptible to application

effects; where the vacuum instrument is located within the process can be critical, as can the

mix of gases present. The vacuum specialist cannot resolve all of these issues, but in many cases

their participation will be essential if effective solutions are to be devised.

This talk will include a broader discussion of these issues, some examples of past efforts of this type,

and a discussion of vacuum instrumentation characteristics that should be considered in resolving

real world problems. This will include discussion of reference leaks, Spinning Rotor Gages and Residual

Gas Analyzers.

6


PLENARY

5


MONDAY MORNING

4


JUNE 26, 2006

Morning Session

INDEX

ETCHC 9

RIVA-TF 20

WS-18 29

JUNE 26, 2006

Afternoon Session

ETCHC 36

RIVA-TF 41

WS-18 50

JUNE 27, 2006

Morning Session

JS1: WS-20- RIVA-ETCHC 57

WS-18 66

JUNE 27, 2006

Afternoon Session

JS1: WS-20- RIVA-ETCHC 74

WS-18 80

JUNE 28, 2006

Morning Session

JS2: WS-20-ETCHC 97

WS-18 105

RIVA-SS 87

JUNE 28, 2006

Afternoon Session

Poster Session : RIVA-ETCHC-WS-20 111

Plenary Lecturers

Ch. Tilford 6

J. Verhoeven 55

H. Högberg 85

3


FOREWORD

The present book contains de abstracts of plenary lecturers, invited and oral

presentations as well as poster presentations. The abstracts have been distributed

according to their scheduled presentation of the corresponding session

of the Conference.

The abstract correspond to the main parallel activities of:

6TH IBERIAN VACUUM MEETING, RIVA-6

4th EUROPEAN TOPICAL CONFERENCE ON HARD COATINGS, ETCHC-4

WS-18: VACUUM MEASUREMENT, LEAK DETECTION AND CALIBRATION AND

VACUUM QUALITY CONTROL

WS-20: OPTICAL AND DECORATIVE COATINGS

Two join sessions has been scheduled the first one to present aspects of the

Thin Films with the workshop devoted to Optical and Decorative Coatings and

the second one is related with hard coatings and tribology.

Presentations related with vacuum measurements has been organised in a

workshop with aspects of the leak detection and vacuum quality control.

Edited by the Asociación Española del Vacío

Madrid. Spain

The Organising Committee and the Editor are grateful to the authors for

their contributions, specially the significant contributions of the Portuguese

scientific community. We also thank the International Programme Committee

for their work in the reviewing of the abstract. A special acknowledge is

to Professor Ángela Calvo for her work in preparing of the local arrangement.

We also thank the University of Salamanca for all the facilities.

José L. de Segovia

Editor

2


Sigilum Universitatis Studii Salamantini

6TH IBERIAN VACUUM MEETING, RIVA-6

12 REUNIÓN ESPAÑOLA DEL VACÍO Y SUS APLICACIONES, REVA-12

REUNIÂO PORTUGUESA DE VÁCUO E SUAS APLICAÇÕES, RIVA-6

4th EUROPEAN TOPICAL CONFERENCE ON HARD COATINGS, ETCHC-4

WS-18: VACUUM MEASUREMENT, LEAK DETECTION AND CALIBRATION AND

QUALITY CONTROL IN ADVANCED INDUSTRIES

WS-20: OPTICAL AND DECORATIVE COATINGS

June 26-30, 2006

Abstract Book

EDITORS:

José L. de Segovia

Instituto de Ciencia de Materiales de Madrid. CSIC. ES

O. Teodoro

Iniversidade Nova de Lisboa. PT

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