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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.61: Poster

Montag, 8. März 2004, 18:00–21:00, Bereich C

Surface photovoltage of thin organic layers on single-crystal metal and semiconductor surfaces — •Sebastian Teich, Stefan Grafström, Christian Loppacher, Ulrich Zerweck, and Lukas Eng — Institute of Applied Photophysics, University of Technology Dresden

Surface photovoltage (SPV) investigations of ultrathin organic films on metal and semiconductor substrates with a unique sensitivity of < 1 mV are reported. This is achieved with a novel phase-sensitive method based on an accurate measurement of the light-induced shift of the ultraviolet (UPS) or x-ray (XPS) photoemission spectrum under power-modulated illumination of the sample. Furthermore, in order to derive local SPV information with high spatial resolution, we use similar modulation methods, however involving scanning tunneling and atomic force microscopy rather than XPS/UPS. Our SPV studies provide access to electronic properties of semiconductor surfaces and interfaces, including in particular organic-inorganic interfaces. We demonstrate the versatility of our SPV techniques for thin films of perylene-tetracarboxylic dianhydride (PTCDA) and Cu-tetra-3,5 di-tertiary-butyl-phenyl porphyrin (Cu-TBPP) on various substrates, including Cu(100) and Ge(100).