Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 24: Postersitzung (Epitaxie und Wachstum, Oxide und Isolatoren, Elektronische Struktur, Oberfl
ächenreaktionen, Adsorption an Oberfl
ächen, Organische Dünnschichten)

O 24.71: Poster

Mittwoch, 26. März 2003, 14:30–17:30, P1

Growth of ultrathin p-Quaterphenyl films on Gold surfaces — •Stefan Müllegger and Adolf Winkler — Institute for Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria

Within the last years the research on conjugated organic molecules has steadily risen due to the extraordinary optical and elecronic properties. Our work focuses on p-quaterphenyl (4P) and its early stages of growth on a Au(111) and a polycrystalline Au substrate, investigating the adsorption/growth of ultrathin 4P films grown by vacuum-deposition. The influence of typical parameters like the substrate temperature, the evaporation rate and surface contamination as well as the 4P growth on a more sophisticated substrate morphology (a stepped Au(433) surface) were studied via TDS, XPS, AES and optical microscopy. Analysis of the TDS spectra according to the Polanyi-Wigner-equation allowed us to calculate the desorption energy as well as the pre-exponential factor of 4P for the (sub)monolayer and the early multilayer regime. We also found evidence of a dissociative adsorption of 4P on thoroughly cleaned Au surface. 4P on Au(111) shows a layer-by-layer growth at low temperatures (93K). At higher temperatures (300K) the film morphology changes into a Stransky-Krastanov-type showing a pronounced growth of crystalline 4P needle-like structures. This work has been supported by the Austrian Fond zur Förderung der wissenschaftlichen Forschung, Proj. No. P15625.