Plenarvorträge - DPG-Tagungen

Dünne Schichten Mittwoch
multilayers deposited the first time by pulsed laser deposition, the interface
roughness strongly depends on the used metal.
Differences between the polymer-metal systems are discussed with respect
to the different diffusion coefficients, reactivities and growth mechanisms
of the used metals on the polymer surface.
DS 14.2 Mi 14:45 HS 32
In-situ x-ray diffraction during sputtering of Shape Memory
Alloy (SMA) Ni-Ti thin films — •R.M.S. Martins 1,2 , N.
Schell 1 , F.M.B. Fernandes 2 , and R. Silva 2 — 1 Institute of Ion
Beam Physics and Materials Research, Forschungszentrum Rossendorf,
P.O. Box 510119, D-01314 Dresden, Germany — 2 CENIMAT, Campus
da FCT/UNL, 2829-516 Monte de Caparica, Portugal
Ni-Ti thin films present great advantages for the fabrication of microactuactuators.
The phase transformation and precipitation which are responsible
for the shape memory effect have been widely studied in bulk
material and thin films. However, in-situ studies have been limited to the
aging/annealing treatments after deposition. In-situ study of the sputter
deposition of Ni-Ti thin films has not yet been reported. Thus a magnetron
sputter deposition chamber has been installed into the six-circle
diffractometer of the ROssendorf BeamLine (ROBL-CRG) at the ESRF,
Grenoble [1], and in consequence the crystallization kinetics have been
followed in situ by x-ray diffraction during sputter deposition of Ni-Ti
thin films.
[1] W. Matz, N. Schell, J. Bøttiger et al., Rev. Sci. Instr. 72, 3344 (2001)
DS 14.3 Mi 15:00 HS 32
Early Stages of Self-assembled Nanostructure Formation during
Cu Deposition onto VSe2 Crystals — •S. Hollensteiner 1 ,
E. Spiecker 1 , W. Jäger 1 , H. Haselier 2 , and H. Schroeder 2 —
1 Technische Fakultät der CAU zu Kiel — 2 Forschungszentrum Jülich
Recent investigations have shown that Cu deposition onto surfaces of
layered VSe2 crystals may lead to self-assembled networks of nanostructures.
TEM, SEM and AFM have been applied to characterize evolution,
lateral arrangements, orientations, and the microscopic nature of the surface
structures. The nanostructures were created applying UHV electron
beam evaporation of Cu onto cleaved layered VSe2 crystals. The nominal
Cu coverages are ranging from 0.4 nm to 2.5 nm. At the lowest coverage
large isolated nanostructures with lateral dimensions > 100 nm are observed
having a roof-like tile structure. At coverages of 1 nm and above
a uniform network of linear nanostructures of smaller lateral dimension
(∼ 20 nm) with mainly hexagonal meshes develops on substrate terraces
in addition to the large nanostructures. Like the large nanostructures the
smaller ones are composed of two crystalline strands. Inside the meshes,
a thin layer of a new phase of uniform thickness has evolved being almost
completely contiguous but separates into three equivalent orientation
variants with epitaxial relationship to the substrate. These results
and the absence of Cu clusters point to the formation of an intercalation
phase. A dense network of dislocations has formed at the interface
indicating the presence of in-plane strain. The role of strain for the formation
and evolution of both the nanoroofs and the network of smaller
nanostructures is discussed.
DS 14.4 Mi 15:15 HS 32
Non-linear effects in the Monte Carlo simulation of sputterinduced
surface morphology — •Oluwole E. Yewande, Alexander
K. Hartmann, and Reiner Kree — Institute for Theoretical
Physics, University of Göttingen, Tammannstr.1, 37077 Göttingen, Germany.
We study the ion-beam sputtering of a solid surface using the (2+1)dimensional
discrete Monte Carlo model on a lattice recently introduced 1 .
We have studied two different surface diffusion mechanisms; one without
and the other including a term accounting for Schwoebel barriers, and
at times long enough to observe the dependence of long-time effects on
surface diffusion. At short times, propagating ripple-like periodic height
modulations appear on the surface. The velocity dispersion and the ripple
wavelength obey scaling relations that are in qualitative agreement
with experimental results 2 . At long-times, where non-linear effects are
significant, the ripples vanish, and the surface topography exhibits the
non-linear behaviour S(k) ∼ k −2.5 , governed by the Kardar-Parisi-Zhang
universality class.
[1] A. K. Hartmann, R. Kree, U. Geyer and M. Kölbel, Phys. Rev. B 65,
193403(2002).
[2] S. Habenicht, K. P. Lieb, J. Koch and A. D. Wieck, Phys. Rev. B 65,
115327(2002).
DS 14.5 Mi 15:30 HS 32
Structural evolution in chromium nitride thin films: A
comparison with structure-zone models — •Yvonne Gerbig 1 ,
Corinne Nouveau 2 , and Henry Haefke 1 — 1 CSEM Swiss Center
for Electronics and Microtechnology Inc, Rue Jaquet-Droz 1, CH-2007
Neuchatel, Switzerland — 2 Ecole Nationale Superieure d’Arts et
Metiers, LA.Bo.MA.P, F-71250 Cluny, FranceCluny
The correlation between micro/nanostructure of thin films and their
deposition conditions is scientifically interesting as well as technologically
relevant for the engineering of functional surfaces. In the last decades,
several structure-zone models (SZMs) have been developed for thin films
grown by pvd techniques to improve the under-standing of the depositionstructure
relationship.
The well-known SZMs of Movchan & Demchishin, Thornton and
Messier consider only a few selected deposition parameters. Recently,
Kelly has created a SZM using more universal energy related parameters.
However, all these SZMs were developed for metal thin films and
their extension to other materials, e.g. ceramic thin films, is not clear.
In this study the validity of various SZMs were evaluated for CrN thin
films synthesized through reactive sputtering by varying the most important
deposition parameters. By applying the thickness gradient technique,
the structural and morphological evolution of CrN thin films was
examined using SEM, AFM and XRD. The observed microstructures and
topographical features are discussed and classified as a function of deposition
parameters in a new SZM based on the approaches of Thornton,
Messier and Kelly.
DS 14.6 Mi 15:45 HS 32
Control of surface roughness in amorphous thin film growth
— •Frank Elsholz 1 , Eckehard Schöll 1 , Hans Eichler 2 , Chris
Scharfenorth 2 , and Arkadi Rosenfeld 3 — 1 Institut für Theoretische
Physik, Technische Universität Berlin, Hardenbergstrasse 36, D–
10623 Berlin — 2 Optisches Institut, Technische Universität Berlin, Hardenbergstrasse
36, D–10623 Berlin — 3 Max-Born-Institut, Max-Born-Str.
2a, 12489 Berlin
The growth of optical layers of SiO2 and Nb2O5 on amorphous substrates
is investigated. We develop a kinetic Monte-Carlo model which
mimics the amorphous structure by randomly fluctuating binding energies.
The resulting surface profiles are characterized by their root mean
square roughness, height-height correlation functions, and growth exponents.
For strong random fluctuations the growth exponents exceed the
value 0.5, in good agreement with experiment.
DS 14.7 Mi 16:00 HS 32
Porous Thin Films Grown by Size-Selected Si-Nanoparticles
— •Felix Voigt 1 , Rudolf Brüggemann 1 , Friedrich Huisken 2
und Gottfried H. Bauer 1 — 1 Fakultät V, Institut für Physik, CvO-
Universität Oldenburg, 26111 Oldenburg — 2 Laborastrophysik-Gruppe,
Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, 07743
Jena
Size selected Si-nanoparticles (Si-nc) with diameters ≥ 3 nm prepared
in a flow reactor with CO2 laser induced SiH4 decomposition and showing
strong luminescence in the visible regime after oxidation of their
surface [1] have been accumulated as thin films on different substrates.
These films contain clusters of conglomerated Si-nc which conserve the
electronic properties of the single Si-nc such as the compression of electronic
wave functions which has been verified by spectral pl-measurements.
The degree of volume filling has been analyzed experimentally to about
0.3. This number is supported by a simplified numerical stick-ball model
for the local arrangement of the Si-nc versus film growth time. We
have studied the growth of these porous thin films by simultaneous coplanar
charge transport measurements (interdigital metal contacts) and see
three regimes: i) negligible transport at the beginning of film growth due
to missing connections, ii) a superlinear increase of current with exponent
3/2 which will be discussed in terms of percolation transport, and iii) a
linear increase with further film thickness. [1] G. Ledoux, O. Guillois, D.
Porterat, C. Reynaud, F. Huisken, B. Kohn, V. Paillard, Phys. Rev. B.
62, 15 942 (2000).