The possibility was discussed that, independent of the polytype, large electronic correlation effects give rise to semiconducting SiC surfaces with [111] or orientations. The most important surface translational symmetries (√3 x √3)R30° and 3 x 3 were considered. The discussion was based on the detailed knowledge of the surface atomic geometries and the electronic structures derived for these geometries using a local density approximation for exchange and correlation. It was argued that the resulting half-filled, weakly dispersive dangling-bond bands within the fundamental gaps were split according to a Hubbard interaction parameter U, and that the surface systems underwent a Mott–Hubbard transition. Such a physical picture provides a qualitatively correct account of the single-particle excitation spectra either inferred from angle-resolved photoemission and inverse photoemission experiments or obtained from scanning tunnelling spectroscopy. The gap opening and hence the Hubbard U parameter were considered in terms of their dependence on the surface reconstruction as well as the SiC polytype.

Electron Correlation Effects on SiC(111) and SiC(0001) Surfaces. F.Bechstedt, J.Furthmüller: Journal of Physics - Condensed Matter, 2004, 16[17], S1721-32