Density functional theory was used to study the formation and properties of native defects in 3C-SiC. Extensive calculations were made of the formation of point defects and of the stability of self-interstitials. It was found that although there was good agreement with regard to the formation of vacancies and antisite defects, between the present and previous calculations, a large disparity appeared with regard to the formation of self-interstitials. The most favored configurations for C interstitials were <100> and <110> dumb-bells, with formation energies of 3.16 to 3.59eV, and the most favored Si interstitial was tetrahedral Si surrounded by four C atoms; with a formation energy of 6.17eV. The present density functional theory results were also compared with those of molecular dynamics simulations performed by using Tersoff potentials and published parameters. The formation energies of vacancies and antisite defects, as obtained by molecular dynamics calculations, were in good agreement with those obtained by density functional theory calculations. However, the molecular dynamics calculations yielded different results for interstitial energies and structures that depended upon the cut-off distances used in Tersoff potentials. The results provided guidelines for evaluating the quality and fit of empirical potentials for the large-scale simulation of irradiation damage and defect migration in SiC.

Ab initio and Empirical-Potential Studies of Defect Properties in 3C-SiC. F.Gao, E.J.Bylaska, W.J.Weber, L.R.Corrales: Physical Review B, 2001, 64[24], 245208