Behavior of 3d-transition metals in different SiC polytypes

The electronic and structural properties of isolated 3d-transition metal impurities in 3C-, 4H-, and 2H-SiC polytypes have been investigated by total energy ab initio methods. The configurational stability, spin states, formation and transition energies of substitutional (Si sub-lattice) Ti, V, and Cr impurities in several charge states have been computed. Our results are discussed in the context of available experimental data on electrically active centers in SiC.