Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)
O 36.10: Poster
Dienstag, 15. März 2011, 18:30–22:00, P4
Structural and electronic properties of thin organic heterointerfaces SnPc/PTCDA/Ag(111) — Mark Häming1, •Christoph Sauer1, Michael Greif1, Achim Schöll1, and Friedrich Reinert1,2 — 1Universität Würzburg, Experimentelle Physik VII, D-97074 Würzburg — 2KIT, Gemeinschaftslabor für Nanoanalytik, D-76021 Karlsruhe
Knowledge about the structural and electronic properties of organic heterointerfaces is of vital importance for electronic devices based on organic semiconductors. Yet information about these systems is still scarce due to difficulties in preparing well defined interfaces. With tin-phtalocyanine (SnPc) deposited on a Ag(111) surface precovered by perylene-tetracarboxylic acid dianhydride (PTCDA) we present a well suited model system to gain insight into such heterointerfaces. Photoelectron spectroscopy (XPS and UPS) as well as near edge X-ray absorption fine structure (NEXAFS) studies are applied in order to gain both structural and electronic information. Distinct features in core-level and valence spectra allow us to unambiguously distinguish between both molecules. We show clear evidence that SnPc forms a flat lying wetting layer on top of PTCDA with a mainly physisorptive character. Moreover a rigid level shift of all spectroscopic SnPc features with respect to the homomolecular SnPc films is observed, similar to what is known for Schottky contacts, which corresponds to a change in work function. We demonstrate that the built-in electric field at the interface can be explained by the formation of an interface dipole, which extends over several adsorbate monolayers.