Super-cell calculation of the nitrogen defect in diamond and cubic silicon carbide

The nitrogen point defect in diamond and cubic SiC was studied using an ab-initio plane wave pseudopotential approach that highlights the differences in the conduction bands of the two materials. Each N defect energy level is located relative to the various energy bands. The N defect level in diamond shows very little dispersion through the bands, which is indicative of its localized character. On the contrary, in cubic SiC the defect is far less localized, with the level essentially depending on the occupancy of either the C or Si site. Both sites may give n-type behavior, but N on the C site is preferred, with a defect level substantially pinned to the conduction band. (C) 2000 Published by Elsevier Science S.A.