Berlin 2005 – scientific programme
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O: Oberflächenphysik
O 49: Epitaxie und Wachstum II
O 49.5: Talk
Tuesday, March 8, 2005, 16:45–17:00, TU EB407
Real-time study of orientational transitions during organic thin film growth — •Stefan Kowarik1, Alexander Gerlach1, Stefan Sellner2, Frank Schreiber1, Leide Cavalcanti3, and Oleg Konovalov3 — 1Physical and Theoretical Chemistry, Oxford University, United Kingdom — 2Max-Planck-Institut für Metallforschung, Stuttgart, Germany — 3European Synchrotron Radiation Facility, Grenoble, France
We study thin films of the semiconductor diindenoperylene on silica during organic molecular beam deposition (OMBD) using synchrotron surface X-ray scattering. The molecular orientation within the thin film and the related anisotropy in electrical conductivity is of practical relevance for electronic devices. Further, the molecular tilt angle is an additional and qualitatively new degree of freedom in growth compared to inorganic / atomic systems. To understand and therefore control growth in OMBD important alterations from inorganic growth have to be included in established growth models. For example, molecular tilt may change scaling laws, which relate surface roughness to lateral and vertical (film thickness) length scales (1). We report on our in-situ and real-time experiment during OMBD growth. It provides evidence for changes of the out-of-plane and in-plane lattice parameters with time, and, importantly, with changes of the molecular tilt angle. We discuss our findings on the orientational transition, combining structural knowledge from the real time measurements with post-growth information on film roughness and morphology.
1. A. C. Dürr et al., Phys. Rev. Lett. 90 (2003) 016104