Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 31: Organische Dünnschichten II
O 31.13: Vortrag
Donnerstag, 27. März 2003, 18:00–18:15, HSZ/02
Influence of growth parameters on the molecular orientation in perylene thin films on Al2O3/Ni3Al(111) — •M. B. Casu, A. Schöll, D. Hübner, Y. Zou, K. R. Bauchspiess, C. Heske, and E. Umbach — Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg
Organic Field Effect Transistors (OFETs) belongs to a rapidly developing field and many efforts are directed towards their optimization. We investigated thin films of perylene, one of the promising candidates as active material in a Metal-Insulator-Semiconductor (MISFET) structure, on Al203/Ni3Al(111) by Near-Edge X-ray Absorption Fine Structure (NEXAFS). A highly ordered thin layer of Al2O3, which simulates the insulating layer in a MISFET, was obtained by controlled oxidation of a Ni3Al(111) single crystal. Thin films of perylene were grown by using organic molecular beam deposition (OMBD) in-situ, under strictly controlled evaporation conditions in order to obtain well-ordered films. We studied the influence of the growth parameters on the molecular orientation and the consequential changes in the electronic fine structure. We find that it is possible to tune the molecular orientation of perylene by using different sets of growth parameters: in particular, the perylene molecular plane is parallel to the substrate surface when the film deposition rate is low, while the molecules stand upright if a high deposition rate is chosen. The latter result promises that perylene can be used for OFETs and that perylene/Al2O3/Ni3Al(111) is a suitable organic/insulator/substrate model system for the technological challenge of developing optimized MISFET structures based on organic materials.