ICMCTF 2012! - CD-Lab Application Oriented Coating Development

Reaction gases were used CH4 (15 SCCM) and H2 (100 SCCM). Vapor of
B(OCH3)3, the boron source, was carried by H2 carrier gas into the vacuum
chamber with its flow rate of 1 to 6 SCCM. Pressure was 20.0kPa and
microwave power was 1.0 kW. Reaction time was fixed to 3 h. The surface
and cross sectional morphologies of deposits were observed by SEM.
Qualities of the deposits were estimated by Raman spectroscopy. Electrical
resistivities were measured by the four-point probe method.
As a result of the SEM observation, the grain sizes of deposits were 1 to 3
μm. The maximum thickness of 6 μm was obtained for carrier gas flow rate
; 3 SCCM. From the Raman spectra of the deposits, the broad peak at about
500, 1230 cm^-1 and the weak peak at 1333 cm^ -1 were observed for
each samples. These peaks due to including high concentration of boron in
the films. In addition, the intensities of the peaks at 1333 cm^ -1 were
decreased with increasing of the carrier gas flow rate. As a result of the
electrical resistivity measurements by the four-point probe method, the
electrical resistivities of boron-doped diamond films decreased with
increasing of carrier gas flow rate. The minimum electrical resistivity of
2.5×10^ -1Ω・ cm was obtained for carrier gas flow rate ; 6 SCCM.
As a conclusion, the boron-doped diamond films were fabricated with each
carrier gas flow rates. In the Raman spectra of the films, the peaks caused
high boron inclusion were observed.
3:30pm B2-2-7 Low temperature chemical vapor deposition of boroncarbon
films for use in neutron detectors, H. Pedersen
(henke@ifm.liu.se), Linköping University, Sweden, C. Höglund, European
Spallation Source ESS AB/ Linköping University, Sweden, J. Birch, J.
Jensen, A. Henry, Linköping University, Sweden
A novel design for neutron detectors based on the isotope 10 B instead of 3 He
has been suggested by the European Spallation Source (ESS), to overcome
the very limited availability of 3 He. In the detector design, very large area
aluminum blades are coated with a thin film containing high amounts of
10 B. 10 B4C was chosen as the thin film material instead of pure 10 B, since it
is easier to handle in a deposition process and due to its high resistance
towards oxidation and wear. Here we demonstrate the synthesis of thin,
amorphous, boron-carbon films at low temperature (400-600 °C), by
thermally activated CVD using the organoborane triethylboron, B(C2H5)3,
(TEB) as single precursor. Since the neutron detectors will be based on
aluminum, there is an upper temperature limit of approximately 600 °C,
which limits a number of possible CVD-processes and also the aluminum
substrate prevents the use of BCl3 as boron precursor. Deposition by TEB is
done on both single crystalline Si (100) substrates and aluminum plates; the
deposition rate at 600 °C was close to 1 µm/h in argon and 0.35 µm/h in
hydrogen. The film density, as measured by X-ray reflectivity (XRR), for
films deposited at 600 °C in hydrogen was 2.42 g/cm 3 (97 % of bulk B4C)
and 2.14 g/cm 3 (86 % of bulk) for films deposited at 600 °C in argon. The
atomic content of the deposited films were analyzed by Time of Flight
Elastic Recoil Detection Analysis (ToF-ERDA), films with B/C-ratio of 4.6
and 3.6 were deposited at 600 °C in hydrogen and argon respectively, the
hydrogen content in the films was 3-4 at%, regardless of deposition
ambient. Both the film composition and film density was found to vary
significantly with deposition temperature and deposition ambient. Based on
our results, a deposition mechanism for boron-carbon films from TEB,
where the TEB molecule is decomposed to BH3 and hydrocarbons, is
suggested.
3:50pm B2-2-8 Synthesis of diamond/carbon nanotube composite thin
films by chemical vapor deposition, L. Yang, Q. Yang
(qiaoqin.yang@usask.ca), Y. Li, Y. Tang, C. Zhang, L.L. Zhang, University
of Saskatchewan, Canada
Diamond/Carbon nanotube (CNT) composite thin films have been
successfully synthesized on silicon wafers using both microwave plasma
enhanced chemical vapor deposition and hot filament chemical vapor
deposition (CVD) technique. Iron was used as catalyst for CNT growth, and
a mixture of CH4 andH2 gases was used to grow both diamond and CNTs.
The synthesized thin films were characterized by Raman spectroscopy,
transmission electron microscopy, scanning electron microscopy, X-ray
diffraction, nanoanalyzer, and field electron emission measurements. The
results show that diamond was deposited with high nucleation density and
high purity, and the CNTs synthesized can be either randomly distributed or
vertically aligned depending on the deposition conditions. The results has
demonstrated that composite films with well aligned CNT arrays and
nanocrystalline diamond can be achieved and the films exhibit superior
field electron properties including large field enhance factor, excellent
current stability and very low turn on field.
Thursday Afternoon, April 26, 2012 86
4:10pm B2-2-9 Effects of ammonia/acetylene mixtures on the
properties of carbon films prepared by thermal chemical vapor
deposition, L.H. Lai, S.T. Shiue (stshiue@dragon.nchu.edu.tw), National
Chung Hsing University, Taiwan
When ammonia is added in acetylene to form carbon films using thermal
chemical vapor deposition, effects of different ammonia/acetylene ratios on
the deposition rate and microstructures of carbon films are investigated. The
deposition temperature, working pressure, and deposition time of the
thermal CVD process were set to 1113 K, 8 kPa, and 25 min, respectively.
The total mass flow rate of acetylene and ammonia were kept at 40
cm 3 /min, and five kinds of carbon films were prepared with the
ammonia/acetylene ratio of 0, 4/36, 8/32, 12/28, 16/24, and 20/20.
Experimental results indicate that the deposition rate of carbon films
decreases as the ammonia/acetylene ratio increases. The mean crystallite
size and ordered degree of carbon films increase with increasing the
ammonia/acetylene ratio. Moreover, when the ammonia/acetylene ratio
increases, the carbon films have more sp 3 carbon atoms and shift to
diamond -like. Few nitrogen and hydrogen atoms are incorporated into
carbon films. The deposition rate of carbon films is proportional to the
partial pressure of acetylene with a power of about eighth order, and thus,
the pyrolysis of acetylene with added ammonia is controlled by the
adsorption process of sixteen-carbon species on the substrate. The results of
thermal CVD carbon deposition using acetylene and ammonia are compared
with those using acetylene and nitrogen.
4:30pm B2-2-10 Hollow-Cathode Deposition of Thin Films Via Metal
Hydride Formation and Decomposition, S. Muhl (muhl@unam.mx),
Universidad Nacional Autónoma de México - Instituto de Investigaciones
en Materiales, Mexico, . Lopez, IIM-UNAM, Mexico, Y. Pena-Rodriguez,
Autonomous University of Madrid, Spain
Approximately 30 to 40 years ago the group of Stan Vepřek of the
University of Zurich described that thin films of polycrystalline silicon
could be prepared utilizing a reversible chemical reaction. In their paper
they described how pieces of silicon were exposed to a low-pressure highdensity
hydrogen plasma promoting the formation of volatile silicon
hydride, this was then transported within the reactor to a hot substrate which
caused the decomposition of the hydride and the deposition of the silicon
film.
Hydrogen plasmas have also been used for chemical etching of various
materials and, for example, in the case of the deposition of diamond films
the preferential etching of sp 2 bonded carbon is considered to be of
fundamental importance.
In this paper we describe the etching of a metal (Mo or Ni) by hydrogen
which was plasma-activated in a RF hollow cathode where the water-cooled
cylindrical cathode was lined with the appropriate metal. The metal hydride
vapour generate in the plasma was directed to quartz substrates which were
maintained temperatures in excess of 300 o C. The metal hydride was
thermal decomposed and a thin film of the metal was deposited. A special
substrate heater was constructed such that four quartz substrates could be
simultaneously exposed to the metal hydride vapour, but with each substrate
at a different temperature; each approximately 20 o C less than the
neighbouring one. In this way, depositions under identical conditions could
be carried out at the same time but at four different temperatures. We report
the deposition rate as a function of the substrate temperature and the RF
plasma power applied to the hollow cathode.
Hard Coatings and Vapor Deposition Technology
Room: Royal Palm 1-3 - Session B6-2
Coating Design and Architectures
Moderator: C. Mitterer, Montanuniversität Leoben, Austria,
M. Stüber, Karlsruhe Institute of Technology, Germany
1:30pm B6-2-1 A Knowledge-Based Approach for Optimized Coating
Architecture, R. Daniel (Rostislav.Daniel@unileoben.ac.at), J. Keckes, C.
Mitterer, Montanuniversität Leoben, Austria INVITED
Physical properties of nanocrystalline thin films are strongly related to their
structure. It, in turn, depends on the deposition conditions, which affect
atomistic processes acting during film growth. An understanding of the
growth-structure-property relations in thin solid films is thus crucial in
optimizing their performance. The attempt of this study is to reveal the
origin of depth-profile variations in film texture, morphology, stress state
and thermal properties based on the evolutionary nature of the film structure
due to competitive growth. We will demonstrate how the variation in the
stress state and thermal properties is related to the volume fraction of grain
boundaries, which typically develops in nanocrystalline films to a different