Hamburg 2001 – wissenschaftliches Programm
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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 13.69: Poster
Montag, 26. März 2001, 19:00–22:00, Foyer zu B
Theory of structural and electronic properties of SiC surfaces — •Fu-He Wang, Peter Krüger, and Johannes Pollmann — Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10 , 48149 Münster
SiC is unique in that it is a IV-IV compound semiconductor with a special combination of exceptional properties. In particular, its surfaces show a very intriguing reconstruction behavior. In this contribution we present first-principle results for cubic 3C-SiC(001) and hexagonal 6H-SiC(0001) surfaces. The calculations have been carried out within local density approximation employing supercells and normconserving pseudopotentials. Gaussian orbitals are used for an efficient description of the wave functions. For the Si-terminated SiC(001)-c(4×2) surface, an interpretation of recent ARPES measurements will be given on the basis of our missing-row asymmetric-dimer model which is found to be more favorable than the alternating up and down dimer model. In order to contribute to an interpretation of very recent results from STM and ARPES measurements for the carbon terminated SiC(001)-c(2×2) surface we have investigated a number of conceivable reconstruction models showing either symmetric or asymmetric dimers. Finally, we address C- and Si- terminated 6H-SiC(0001)-(√3 × √3) surfaces. They turn out to be very interesting Mott-Hubbard insulators. Oxygen adsorption on the C-terminated SiC(0001) surface leads to the formation of a Si2O3 silicate adlayer. The corresponding surface band structure which we have calculated employing self-interaction and relaxation-corrected pseudopotentials is in good agreement with experimental data.