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O: Oberflächenphysik

O 13: Postersitzung (Adsorption auf Oberfl
ächen, Oberfl
ächenreaktionen, Elektronische Struktur, Epitaxie und Wachstum, Halbleiteroberfl
ächen und Grenzfl
ächen, Oxide und Isolatoren)

O 13.77: Poster

Montag, 26. März 2001, 19:00–22:00, Foyer zu B

Structure determination of the Sb/Ge(113) surface reconstruction by surface x-ray diffraction — •A. Hirnet¹, M. Albrecht¹, M. Gierer¹, B. Jenichen² und W. Moritz¹ — ¹Institut für Kristallographie und Angewandte Mineralogie, Universität München, Theresienstr. 41, 80333 München — ²Paul Drude Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin

We investigated the Sb adsorption on Ge(113) by grazing incidence x-ray diffraction. The Sb superstructure was prepared by depositing 3/4 ML Sb from a Knudsen cell on the clean Ge(113) surface at room temperature and subsequent annealing to about 800 K. With a high resolution LEED system (SPA-LEED) a (2x2) superstructure with sharp spots is observed. From this structure an x-ray data set was taken with our UHV six circle diffractometer at the wiggler beam line W1.1. The spots at the (2x2) positions were too weak to be measured. At a wavelength of 1.2 Å 250 symmetrically inequivalent structure factors were recorded. In the analysis the Sb-positions and the Ge-positions in the top 4 substrate layers, isotropic temperature factors and one scale factor have been refined, altogether 69 free parameters. The analysis showed that Sb occupies three symmetrically inequivalent sites, breaks one Ge-Ge bond and forms a dimer with a bond length of 2.875 Å. This model has been proposed previously by Dabrowski et al. [1] for Sb/Si(113).

[1] J. Dabrowski, H.J. Müssig, G. Wolff, S. Hinrich, Surf. Sci. 411, 54 (1998).