Plenarvorträge - DPG-Tagungen

Dünne Schichten Montag
implantation are compared for the various materials investigated. The
results are discussed in the framework of models taking into account
DS 3 Ionenimplantation III
fundamental physical properties of the semiconductors.
Zeit: Montag 14:30–16:00 Raum: HS 31
DS 3.1 Mo 14:30 HS 31
Kinetics of ion-irradiation induced stress modifications in thin
film of different microstructure — •S.G. Mayr — I. Physikalisches
Institut, Georg-August-Universität Göttingen, Tammannstr. 1, 37077
Göttingen
Ion beam irradiation induced changes in the stresses operating in thin
films are correlated with the thermodynamic phases of the films and the
evolution in the films microstructure and morphology. We investigate using
a combination of experiments and molecular dynamics computer simulations
the kinetics of the processes, which lead to residual stress changes
in amorphous, nanocrystalline, columnar polycrystalline and single crystal
thin films. It is shown that - while local viscous relaxation within the
collision cascade underlies all stress changes - the initial microstructure
controls the final state of stress.
Financially supported by the DFG - SFB 602, TP B3.
DS 3.2 Mo 14:45 HS 31
Charakterisierung mittels Plasma-Immersions-Ionenimplantation
und -Deposition hergestellter DLC-Schichten — •Götz
Thorwarth 1,2 , Claus Hammerl 2 , Marcus Kuhn 2 , Walter
Assmann 3 und Bernd Stritzker 1 — 1 Lehrstuhl für Experimentalphysik
IV, Universität Augsburg, 86135 Augsburg — 2 AxynTeC
Dünnschichttechnik GmbH, Am Mittleren Moos 48, 86167 Augsburg
— 3 Sektion Physik der LMU München, Am Coulombwall 6, 85748
Garching
Diamantähnlicher Kohlenstoff (DLC) besitzt dank seiner speziellen
mechanischen, chemischen und elektrischen Eigenschaften ein großes
Anwendungspotential. Die Einsetzbarkeit des Materials insbesondere
im mechanischen Bereich erfordert den Einsatz großflächiger Behandlungsverfahren
mit hohen Beschichtungsraten. Ein diesen Ansprüchen
nahekommender Prozeß konnte auf Basis der Plasma-Immersions-
Ionenimplantation und -Deposition (PIII&D) entwickelt werden. Die resultierenden
Schichten wurden mittels Elastischer Rückstoßspektroskopie
(ERDA), Ramanspektroskopie, verschiedener tribologischer Verfahren
(Tribotest, Nanoindent, Impakt- und Scratchtest) sowie Korrosionstests
charakterisiert. Der Vortrag gibt einen Überblick über die Ergebnisse und
diskutiert die Abhängigkeit von den PIII&D–Prozeßparametern.
DS 3.3 Mo 15:00 HS 31
Plasma Immersion Ion Implantation of Martensitic Stainless
Steel — •Darina Manova, Stephan Mändl, Horst
Neumann, and Bernd Rauschenbach — Leibniz-Institut für
Oberflächenmodifizierung, Leipzig
Lattice expansion after energetic nitrogen implantation at medium
temperatures around 400 ◦ C, in conjunction with a significant wear reduction
by several orders of magnitude, is the common result for austenitic
stainless steels. In contrast, martensitic stainless steels are rarely investigated.
In this comprehensive investigation, different martensitic steel
grades are implanted with nitrogen using plasma immersion ion implantation
in the temperature range between 350 and 400 ◦ C. A closed surface
layer of expanded martensite extending several micrometer into the
sample was observed in all samples with a hardness of up to 2000 HV
and a wear reduction by two orders of magnitude. The layer thickness
is a function of steel grade and implantation parameters. Metallographic
cross-sections are investigated to correlate the mechanical properties with
the microstructure.
DS 3.4 Mo 15:15 HS 31
Ni depletion of a NiTi surface by ion implantation for biomedical
applications — •Natalia Shevchenko and Manfred Maitz
— FZ Rossendorf, Postfach 510119, 01314 Dresden
The NiTi alloy is interesting for medical applications because of its
either superelastic or memory shape properties. However, clinical acceptance
of the alloy still is limited due to its high nickel content.
The aim of this work is to reduce the Ni concentration in a NiTi surface
by ion implantation and study the influence on surface stability and
biocompatibility.
Modification of the NiTi samples was performed by N or/ and Ar
ion implantation at different parameters: ion energy (20 - 40 keV and
200 keV), fluence (10 17 − 10 18 cm −2 ), substrate temperature (RT - 400
C). The modified layers were examined by Auger electron spectroscopy,
grazing incidence X-ray diffraction analysis and transmission electron microscopy.
The corrosion resistance and biocompatibility were investigated
by the electrochemical corrosion analysis and cell culture tests with bone
forming cells, respectively.
Ion implantation could reduce the surface nickel content down to approx.
0.5 at %. Below the Ni depleted surface a Ni enriched zone is
formed, which indicates an increased mobility either of Ni from the surface
to the bulk or of Ti from the sub-surface to the surface. A reactive
diffusion mechanism for the nickel depletion in this system is discussed.
The corrosion stability increases by this treatment. In preliminary studies
with bone forming cells no decrease in biocompatibility was seen by
this treatment.
DS 3.5 Mo 15:30 HS 31
Swift heavy ion beam induced solid-state reaction at metaloxide/silicon
interfaces — •Ammar Elsanousi 1 , Wolfgang
Bolse 1 , Beate Schattat 1 , and Siegfried Klaumünzer 2 —
1 Institut für Strahlenphysik, Universität Stuttgart — 2 Hahn-Meitner
Institut, Berlin
We have studied the induced effects that occur at the interfaces of
metal-oxide/silicon bi-layers due to the irradiation with swift heavy
ions. Three different systems were investigated: NiO/Si, TiO2/Si, and
Fe2O3/Si. The irradiations were carried out at liquid nitrogen temperature
with ions ranging from 140 MeV Kr 10+ to 350 MeV Au 26+ at fluences
up to 3·10 15 ions/cm 2 . The samples were characterized by means of
Rutherford Backscattering Spectrometry (RBS), Scanning Electron Microscopy
(SEM) and X-Ray Diffraction (XRD). The as-deposited NiO
films exhibit a large shift and broadening of the XRD peaks, which indicates
strong in-plane stresses. At low irradiation fluences NiO/Si and
Fe2O3/Si showed the usual random walk mixing behavior △σ 2 = kφ,
while in TiO2/Si a non-linear scaling △σ 2 = kφ + mφ 2 was observed,
which indicates that mixing is driven by a chemical solid-state reaction.
At higher fluences plateau-formation was observed at the low-energy Niedge
in the RBS-spectra of NiO/Si, which indicates the formation of the
Olivinephase Ni2SiO4. However, the XRD-spectra did not show any evidence
for the crystalline form of this compound. At very high fluences,
dewetting occurs for NiO and Fe2O3 and the former coherent oxide films
agglomerate in small islands with micrometer dimension on top of the Si
substrate.
DS 3.6 Mo 15:45 HS 31
Ionenstrahlinduzierter Atomtransport an den Grenzflächen
dünner Alkalihalogenid-Schichten — •Hartmut Paulus, Christian
Dais und Wolfgang Bolse — Institut für Strahlenphysik,
Universität Stuttgart
Die Arbeitsgruppe Nukleare Festkörperphysik des Instituts für Strahlenphysik
der Universität Stuttgart hat in den letzten Jahren systematisch
das Mischverhalten dünner Schichtpakete unter Beschuß mit
schnellen Schwerionen untersucht. Bisher wurden Keramik/Keramik, Metall/Keramik
und Metall/Halbleiter Systeme untersucht. Als neue Materialklasse
sind jetzt die Alkalihalogenide dazu gekommen. Diese zeigen
heftige Reaktionen auf den Beschuß mit schnellen Schwerionen: das Material
schwillt, bildet Hügel auf der Oberfläche und weist sehr hohe, stark
richtungsabhängige Sputterraten auf [1]. Diese Eigenschaften machen sie
auch für eine Untersuchung hinsichtlich ihres Transportverhaltens an
Grenzflächen interessant. Präsentiert werden erste Ergebnisse der Untersuchung
von Alkalihalogenid-Schichten auf einem SiO2-Substrat, die mit
einer metallischen Sputterbarriere an der Oberfläche abgedeckt waren.
[1] M. Toulemonde, W. Assmann, C. Trautmann, and F. Grüner Phys.
Rev. Lett., 88, 057602 (2002)