Deep gap states of a single vacancy in cubic SiC

The character of relaxation of atoms around a vacancy in cubic silicon carb ide is determined with the help of the empirical potential of Tersoff The r ecursion method of Haydock and Nex is applied to calculate the density of s tates derived from atoms situated around the defect. The outward relaxation of the lattice surrounding a empty site is established. The lattice relaxa tion 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 s emiconducting compounds.