Berlin 2005 – scientific programme
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O: Oberflächenphysik
O 31: Organische Dünnschichten III
O 31.8: Talk
Monday, March 7, 2005, 12:30–12:45, TU EB420
Effect of substrate structure on organic thin film morphology: Oligo-phenylenes on gold. — •Stefan Müllegger1, Stefan Mitsche2, Peter Pölt2, Kathrin Hänel3, Alexander Birkner3, Christof Wöll3, and Adolf Winkler1 — 1Institute of Solid State Physics, Graz University of Technology, Austria. — 2Research Institute for Electron Microscopy, Graz University of Technology, Austria. — 3Physikalische Chemie I, Ruhr Universität Bochum, Germany.
Thin films of organic semiconducting materials are attracting a growing interest both from a scientific and an applications point of view. In particular, the structure and morphology of such films are important, as they influence the (opto)electronic thin film properties. Based on our model systems, oligo-phenylene thin films grown on different Au surfaces by physical vapour deposition under UHV conditions, we demonstrate the significance of the geometric substrate structure for the development of highly anisotropic thin films. This is achieved by applying a properly prepared polycrystalline Au substrate, which comprises a large variety of differently oriented single-crystalline grains. We have applied multiple surface-sensitive techniques like secondary electron microscopy (SEM), electron backscattering diffraction (EBSD) and scanning tunnelling microscopy (STM), in order to reveal the effects of geometric anisotropy of the substrate on the structure and morphology of organic crystal growth. In particular, we could relate the orientation and terrace width of stepped (vicinal) Au surfaces to the orientation of the elongated organic crystals and the corresponding growth mode.