Plenarvorträge - DPG-Tagungen
Plenarvorträge - DPG-Tagungen
Plenarvorträge - DPG-Tagungen
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Dünne Schichten Mittwoch<br />
DS 13 Schichteigenschaften III<br />
Zeit: Mittwoch 16:45–18:00 Raum: HS 31<br />
DS 13.1 Mi 16:45 HS 31<br />
Microtribology of Nanocomposite Self-lubricating Coatings —<br />
•Vladislav Spassov, Imad Ahmed, Giuseppe Bregliozzi, Alan<br />
Savan und Henry Haefke — CSEM Swiss Center for Electronics and<br />
Microtechnology, Inc., Rue Jaquet-Droz 1, CH 2000, Neuchatel, Switzerland<br />
Tribological coatings deposited by sputter PVD or arc PVD methods<br />
from compound targets often contain microparticles embedded in, and<br />
projecting through, the coating. When using macroscopic tribological<br />
characterisation methods such as pin-on-disk (POD) and linear, oscillating<br />
sliding (SRV) tribometer tests, it is difficult to separate the influence<br />
of factors such as debris generation and microparticles. Often the debris<br />
built-up makes it impossible to measure the real friction coefficient of<br />
the coating against the selected material. Therefore, micro-scale analogues<br />
of the abovementioned methods have to be applied in order to<br />
study the tribological properties of a PVD coating without the influence<br />
of debris or microparticles. In the current work, the authors have used a<br />
microtribometer to examine the tribological properties of TiAlCN+MoS2<br />
nanocomposite self-lubricating coatings against 100 Cr 6 (DIN 1.3505)<br />
steel having oscillating relative movement. The results are discussed and<br />
compared to data obtained from macroscopic pin-on-disk tests.<br />
DS 13.2 Mi 17:00 HS 31<br />
Mechanical properties of laser deposited PMMA films — •Erik<br />
Süske 1 , Thorsten Scharf 1 , Peter Schaaf 2 , Elena Panchenko 3 ,<br />
Dorit Nelke 3 , Michael Buback 3 , Harald Kijewski 4 , and Hans-<br />
Ulrich Krebs 1 — 1 Institut für Materialphysik, Tammannstr. 1, 37077<br />
Göttingen — 2 II. Phys. Institut, Tammannstr. 1, 37077 Göttingen —<br />
3 Institut für physikalische Chemie, Tammannstr. 6, 37077 Göttingen —<br />
4 Institut für Rechtsmedizin, Windausweg 2, 37073 Göttingen<br />
Poly-(methyl methacrylate) (PMMA) films were laser deposited at a<br />
wavelength of 248 nm in UHV at substrate temperatures up to 250 ◦ C<br />
and characterized by infrared spectroscopy (FTIR), size eclusion chromatography<br />
(SEC), thermogravimetric analysis (TGA) and microhardness<br />
measurements. The FTIR spectra indicate a chemical structure<br />
closed to the bulk material, probably caused by a radical polymerization<br />
mechanism, with a small amount of cross-linked polymer. Nevertheless,<br />
after deposition the chain length of the PMMA is reduced to about 6000<br />
g/mol. Due to this changes, the mechanical properties of the films vary<br />
dramatically from the bulk polymer, e.g. the hardness increases by a factor<br />
of five. During annealing the mechanical properties of the films can<br />
be systematically varied to values closed to that of bulk samples. The<br />
deposition process and properties of the films are discussed with respect<br />
to changes in chemical structure, number of cross links and chain length,<br />
while the changes in mechanical properties are concerned with relaxation<br />
effects and the stability of the polymer.<br />
DS 13.3 Mi 17:15 HS 31<br />
Effect of Microwave radiation on structural and mechanical<br />
properties of Al2O3 thin films deposited by sol-gel process<br />
— •Phani Ayalasomayajula and Henry Haefke — CSEM Swiss<br />
Center for Electronics and Microtechnology Inc., CH-2007 Nuechatel,<br />
Switzerland<br />
The lower temperatures and shorter processing time associated with<br />
microwave irradiation might be ascribed to the activating and facilitating<br />
effect of microwave energy on solid phase diffusion. Unlike other preparation<br />
methods, microwave heating is generally significantly faster, simpler,<br />
DS 14 Schichtwachstum<br />
and very energy efficient. In the present work, alumina has been chosen<br />
because of its high hardness, chemical resistance, and scratch resistance<br />
properties. Thin films of Al2O3 have been deposited on quartz substrates<br />
at room temperature by a sol-gel dip coating technique. Two kinds of<br />
treatments have been applied to the as-deposited films for comparison:<br />
(1) furnace annealing at different temperatures ranging from 200oC to<br />
1000oC for 5 hours and (2) exposure to different microwave radiation<br />
(2.45 MHz), with powers ranging from 200 W to 1000 W for 5 minutes.<br />
X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy<br />
dispersive x-ray (EDX)analysis techniques have been employed to<br />
characterise the structural, morphological and elemental composition of<br />
the films. Nanohardness indentation tests of the films exposed to microwaves<br />
(600W and above) have shown a hardness of 8.5 GPa with an<br />
elastic modulus of 140 GPa compared to the annealed sample having 3.3<br />
GPa with an elastic modulus 57 GPa.<br />
DS 13.4 Mi 17:30 HS 31<br />
Characterization of the amorphous-crystalline silicon interface<br />
by time resolved surface photovoltage and photoluminescence<br />
techniques — •Abdelazize Laades, Klaus Kliefoth, Rolf<br />
Stangl, Manfred Schmidt, and Walther Fuhs — Hahn-Meitner-<br />
Institut Berlin, Abt. Silizium Photovoltaik, Kekuléstr. 5, D-12489<br />
Berlin<br />
Amorphous silicon/crystalline silicon interfaces (a-Si:H/c-Si) were prepared<br />
by plasma enhanced chemical vapor deposition and analyzed by<br />
time resolved surface photovoltage method (TR-SPV) and photoluminescence<br />
spectroscopy (PL). To characterise the interfaces formed by varying<br />
the process parameters, the c-Si substrate is excited through the a-Si:H<br />
layer by high intensity laser pulses such that the excess carriers are predominantly<br />
generated in c-Si. It is shown that TR-SPV and PL methods<br />
are sensitive to the nonradiative recombination at the a-Si:H/c-Si interface.<br />
A qualitative approach to interpret SPV transients is presented<br />
and discussed. Applying this approach, we come to the conclusion that<br />
the best interface quality is reached at a substrate temperature around<br />
230 ◦ C and that the a-Si:H film thickness in the range between 5 nm and<br />
200 nm has no influence on the a-Si:H/c-Si interface properties.<br />
DS 13.5 Mi 17:45 HS 31<br />
Nachweis akustischer Oberflächenphononen in BNbeschichteten<br />
Kohlenstofffasern — •T. Wittkowski 1 , K.<br />
Jung 1 , B. Hillebrands 1 , S. Stöckel 2 , K. Weise 2 und G. Marx 2<br />
— 1 Fachbereich Physik und Forschungsschwerpunkt MINAS, Technische<br />
Universität Kaiserslautern, 67663 Kaiserslautern — 2 Institut für<br />
Chemie, Physikalische Chemie, Technische Universität Chemnitz, Straße<br />
der Nationen 62, 09107 Chemnitz<br />
Mit der Brillouin-Lichtstreuspektroskopie (BLS) wurden akustische<br />
Oberflächenphononen auf dünnen, unbeschichteten und beschichteten Fasern<br />
nachgewiesen. Die BLS-Analysetechnik greift bei der Messung nicht<br />
in das Materialverhalten ein, sie ist zerstörungsfrei und kann auch bei<br />
komplizierteren Probengeometrien erfolgreich eingesetzt werden.<br />
Die mit der BLS gemessene Geschwindigkeitsdispersion der Rayleigh-<br />
Mode in diesem Schicht-Substrat-System führt zu präzisen Aussagen<br />
über das elastische Verhalten der Bornitridbeschichtung. Die Ergebnisse<br />
dokumentieren den erwünschten Effekt einer deutlichen Verringerung<br />
der Schersteifigkeit der beschichteten im Vergleich zu den unbeschichteten<br />
Fasern im oberflächennahen Bereich. Aus der Dispersion erhält man<br />
zusätzliche Informationen über die Infiltration des Faserbündels während<br />
des thermischen CVD-Beschichtungsprozesses.<br />
Zeit: Mittwoch 14:30–16:15 Raum: HS 32<br />
DS 14.1 Mi 14:30 HS 32<br />
Microstructure of polymer-metal composite thin films grown<br />
by pulsed laser deposition — •Jörg Faupel, Thorsten Scharf,<br />
and Hans-Ulrich Krebs — Institut für Materialphysik, Universität<br />
Göttingen, Tammannstrasse 1, D-37077 Göttingen<br />
Polymer-metal composites have a wide range of applications ranging<br />
from food-packaging to microelectronics. Using an excimer laser of<br />
248nm wavelength and 30ns pulseduration, polymer-metal composites<br />
were prepared in UHV at room temperature. For the polymer matrix<br />
BPA-polycarbonate (PC) was used, as metals Ag, Au, Cu and Pd. The<br />
samples were characterised by x-ray reflectivity and TEM using top and<br />
also cross-sectional view. The size of the spherical Ag and Au grains,<br />
embedded in a PC matrix, can be controlled by the pulse number during<br />
deposition. In the case of Cu and Pd in comparison, smaller and more<br />
grains and also a different growth behaviour is found. For polymer/metal