PNNL

Abstract

Density functional theory (DFT) is used to study the formation and properties of native defects in 3C-SiC. The extensive calculations have been carried out to determine the formation of point defects and the stability of self interstitials. Although there is a good agreement in the formation of vacancies and antisite defects between the present study and previous calculations, a large disparity appears in the formation of self interstitials. It is found that the most stable configuration of interstitials is the C-C dumbbell along the direction at a C site, with a formation energy of 3.16 eV. The present DFT results are also compared with those calculated by molecular dynamics (MD) simulations using the Tersoff potentials, with parameters obtained from the literature. The formation energy of vacancies and antisite defects obtained by MD calculations are in good agreement with those obtained by DFT calculations. However, the MD calculations yield different results for interstitials energies and structures that depend on the cut-off distances used in the Tersoff potentials. The results provide guidelines for evaluating the quality and fit of empirical potentials for large-scale simulations of irradiation damage and defect migration processes in SiC.