Influence of polytypism on elementary processes of ion-beam-induced defectproduction in SiC

Classical molecular dynamics (MD) simulations are performed to investigate elementary ion-beam-induced defect production in 3C- and 4H-SiC. A modified Tersoff potential is used to model the interactions between the atoms. For cases where the C and Si primary knockon atoms (PKAs) start parallel or an tiparallel to the [0001] direction, the threshold PKA energy for defect for mation as well as the final defect configuration and its formation energy a re determined. The elementary defects observed in 3C-SiC and 4H-SiC differ significantly whereas the corresponding threshold PKA energies and the form ation energies of the configurations are mostly similar. In 3H-SiC new site s for C and Si interstitials are found: one site is situated between two C3 Si3 hexagonal rings, the other between a C-3 and an Si-3 trigonal ring. (C) 2001 Elsevier Science B.V. All rights reserved.