A THEORETICAL-STUDY OF THE LOCAL ELECTRONIC-STRUCTURES OF SIC POLYTYPES

The electronic structure of four SiC polytypes has been computed by me ans of the LMTO (ASA+CC) method. It is shown that the results of the c alculations are very sensitive to the choice of the atomic sphere radi i, if the combined corrections are not taken into account in the ASA. The local electronic structure shows a different behaviour between the states in the cubic bilayers and those in the hexagonal ones. It is f ound that the interaction of c and h bilayers plays a major role, givi ng rise to changes in the polarity of the Si-C bonds and to charging o f bilayers. The effect of the lattice distorsion on the local valence electron charge has been investigated and discussed.