Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 40: Elektronische Struktur V

O 40.1: Vortrag

Freitag, 28. März 2003, 11:15–11:30, M\"UL/ELCH

Experimental determination of the Mott-Hubbard parameter U of the (√3 × √3)R30^∘ reconstructed 4H-SiC(0001) surface — •Ralf Ostendorf, Carsten Benesch, and Helmut Zacharias — Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster

The (√3 × √3)R30^∘ reconstruction of silicon carbide is known as a Mott-Hubbard System. Theoretical calculations predict a Mott-Hubbard parameter independent from the underlying polytype. That implies that the (√3 × √3)R30^∘ reconstruction of the 3C-SiC(111), 4H-SiC(0001) and 6H-SiC(0001) surface should show the same band gap of U ≈ 2 eV, although the electronic band structures of the different polytypes are obviously different. So far experimental determinations of the Mott-Hubbard parameter U exist only for the 6H polytype. We present the first determination of U at the 4H-SiC(0001) surface using inverse photoemission spectroscopy. Our experiments show a Mott-Hubbard parameter of U = (2.2 ± 0.2) eV for the 4H- and 6H-polytype as predicted by theory.