PNNL

Abstract

Defect energetics in SiC have been widely studied using Tersoff potentials, but these potentials do not provide a good description of interstitial properties. In the present work, an empirical many-body interatomic potential is developed by fitting to various equilibrium properties and defect formation in bulk SiC, using a lattice relaxation fitting approach. This parameterized potential has been used to calculate defect formation energies and to determine the most stable configurations for interstitials using the molecular dynamics (MD) method. Although the formation energies of vacancies are smaller than those obtained by ab initio calculations, the properties of antisite defects and interstitials are in good agreement with the results calculated by ab initio methods. It is found that the most favorable configurations for C interstitials are and dumbbells on both Si and C sites, with formation energies from 3.04 and 3.95 eV. The most favorable Si interstitial is the tetrahedral interstitial site, surrounded by four C atoms, with formation energy of 3.97 eV. The present results will be discussed and compared with those obtained by others using various empirical potentials in SiC.