The electronic structures and optical properties which were associated with antisite defects in the cubic material were studied. The orbital-dependent local density approximation which was used here gave rise to improved descriptions of the electronic structure near to the energy gap. Most attention was paid to the effects which were caused by the local lattice relaxations around the defects. In the case of compositions which deviated towards higher C contents, a small reduction of the energy gap which was observed experimentally could be explained only if the lattice relaxation was taken into account. The local electronic structure of antisite defects was characterized by s- and p-like resonance states in the valence band. Strong resonances also occurred in the conduction band; especially for CSi. The SiC (CSi) antisite had more (fewer) valence electrons localized in the atomic sphere than did the official Si (C) atom; but this difference was considerably reduced by lattice relaxation. Calculations showed how the presence of point defects modified the shape of the optical functions of the perfect SiC crystal, and how the lattice relaxation had a strong effect upon the fine structure of the optical functions.

The Effect of the Atomic Relaxation around Defects on the Electronic Structure and Optical Properties of ß-SiC. G.Cubiotti, J.Kucherenko, A.Yaresko, A.Perlov, V.Antonov: Journal of Physics - Condensed Matter, 1999, 11[10], 2265-78