Regensburg 2007 – scientific programme
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.10: Poster
Tuesday, March 27, 2007, 18:00–20:00, Poster B
Structural and electronic properties of highly ordered CuPc thin films on differently passivated vicinal silicon surfaces — •Gianina Gavrila1, Teodor Toader1, Stefan Seifert1, Walter Braun2, and Dietrich Zahn1 — 1Chemnitz University of Technology, Semiconductors Physics Department, D-09107 Chemnitz — 2BESSY GmbH, Albert-Einstein-Straße15, D-12489, Berlin
One intriguing way of controlling the orientation of organic molecules on inorganic substrates is by designing the geometric structure of the substrate surface, e.g. by the steps and terraces of vicinal surfaces. Near Edge X-ray Absorption Fine Structure investigations of Copper Phthalocyanine (CuPc) deposition on differently passivated vicinal Si(111)-7x7 surfaces revealed that the molecular orientation of CuPc molecules can be controlled by different substrate pretreatment. On hydrogen passivated vicinal Si(111)-7x7 the individual CuPc molecules adopt a standing upright geometry and form structures aligned parallel to the step edges on the substrate. In contrast, on antimony (Sb)-passivated vicinal Si(111) surfaces columns of CuPc are again predominantly parallel to the step edge direction but the individual molecules are lying flat on the terraces. The electronic properties of such highly ordered CuPc thin films is revealed by means of photoemission spectroscopy (PES). Photon energy dependent measurements performed on thin CuPc films deposited onto Sb passivated vicinal silicon surfaces revealed an intermolecular energy band dispersion of about 0.25 eV for the highest occupied molecular orbitals. The NEXAFS and PES results are correlated with scanning tunnelling microscopy images.