Native defect properties in β-SiC:: Ab initio and empirical potential calculations

There is considerable ambiguity regarding the formation of native defects and their clusters in silicon carbide (SiC), since different empirical potentials give different results. particular for the stability of interstitial configurations. Density functional theory (DFT) is used to study the formation and properties of native defects in beta -SiC. The DFT results are compared with those calculated by molecular dynamics (MD) simulations using the Tersoff potentials, with modified cut-off distances and parameters obtained from the literature. The formation energy of vacancies and antisite defects obtained by DFT calculations are in good agreement with those given by the Tersoff potential, regardless of the cut-off distances, but for interstitials there is a disparity between the two methods, depending on the cut-off distances used in the Tersoff potential. The present results provide guidelines for evaluating the quality and fit of empirical potentials for large-scale simulations of irradiation damage (displacement cascades) and point defect migration (recombination or annealing) in SiC. (C) 2001 Elsevier Science B.V. All rights reserved.