Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 41: Elektronische Struktur III

O 41.3: Talk

Tuesday, March 8, 2005, 11:15–11:30, TU EB107

Unoccupied electronic states on oxidized SiC(0001)-surfaces determined by inverse photoemission — •Kathrin Wulff, Ralf Ostendorf, Carsten Benesch, and Helmut Zacharias — Physikalisches Institut, Universität Münster, Wilhelm-Klemm Strasse 10, 48149 Münster

Starting from the silicon rich (3×3) reconstruction of SiC(0001) we prepared oxidized surfaces by hydrogen etching as well as molecular oxygen exposure ranging from 5000 L to 30000 L. LEED pictures show a (1×1)-reconstructed surface with a faint (√3 × √3)R30^∘ structure after oxidation, indicating a mainly disordered surface with only few patches of long range order. A distinct change in the shape of the Si_LVV AES peak which is similar to spectra taken on pure SiO₂ refers to the existence of Si-O bonds on the surface.

By applying inverse photoemission spectroscopy we find four electronic resonances above the Fermi level. Decreasing intensities with time caused by residual gas phase contaminants identify these structures as possible surface states. Finally, wave-vector resolved measurements show a flat dispersion for each resonance throughout the whole surface Brillouin zone.