Regensburg 1998 – wissenschaftliches Programm

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O: Oberflächenphysik

O 34: Poster (II)

O 34.5: Poster

Donnerstag, 26. März 1998, 20:00–22:30, Bereich C

Ab-initio studies of the c(4×2) reconstruction of β-SiC(001) — •Wenchang Lu, Peter Krüger, and Johannes Pollmann — Institut für Theoretische Physik II -Festkörperphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149 Münster

The reconstruction behaviour of β-SiC surfaces has very recently attracted considerable attention, worldwide, both in experiment and theory. For the Si-terminated (001) surface, several reconstruction models have been reported. In this contribution we address structural and electronic properties of the c(4x2) reconstruction of β-SiC(001) in order to contribute to a better understanding of this surface. The calculations have been carried out within local density approximation employing supercells and normconserving pseudopotentials in separable form. We have investigated a number of models consistent with a c(4x2) reconstruction. Our results show that the configuration of rows of alternately up and down dimers (the AUDD model [1]) has higher energy than the optimal (2x1)-reconstructed surface. We have also investigated an adatom structure with half a monolayer of Si atoms adsorbed on the Si-terminated (001) surface. The adatoms form a missing row reconstruction and show strong dimerization. For this model, we find a dimer-bond length of about 2.3 Å. Measured STM images and height profiles [1], as well as, photoemission data [2] can very well be explained by this model.

[1] P. Soukiassian et al., Phys. Rev. Lett. 78, 907 (1997)

[2] M. L. Shek, Surf. Sci. 349, 317 (1996)