Electron correlation effects on SiC(111) and SiC(0001) surfaces

Abstract

The possibility is discussed that, independent of the polytype, large electronic correlationeffects give rise to semiconducting SiC surfaces with [111] or [0001] orientations. The mostimportant surface translational symmetries and 3 × 3 are considered. The discussion is based on the detailed knowledge of the surfaceatomic geometries and the electronic structures derived for these geometries usinga local density approximation for exchange and correlation. It is argued thatthe resulting half-filled, weakly dispersive dangling-bond bands within thefundamental gaps are split according to a Hubbard interaction parameterU, and that the surface systems undergo a Mott–Hubbard transition. Such a physical pictureprovides a qualitatively correct account of the single-particle excitation spectra eitherinferred from angle-resolved photoemission and inverse photoemission experiments orobtained from scanning tunnelling spectroscopy. The gap opening and hence the HubbardU parameter are discussed in terms of their dependence on the surface reconstruction as wellas the SiC polytype.