Deep gap states of a single vacancy in cubic SiC

Abstract

The character of relaxation of atoms around a vacancy in cubic silicon carbide is determined with the help of the empirical potential of Tersoff. The recursion method of Haydock and Nex is applied to calculate the density of states derived from atoms situated around the defect. The outward relaxation of the lattice surrounding a empty site is established. The lattice relaxation results in the shift of gap states toward the conduction band. Vacancy levels of carbon at 0.5 eV and silicon at 0.45 and 1.98 eV are revealed in the band gap. The obtained results are compared with the experimental ones and with the data of other calculations. The work shows the importance of taking into account the lattice relaxation in examining vacancy states in semiconducting compounds.