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

Classical molecular dynamics simulations were performed to investigate elementary ion-beam-induced defect production in 3C- and 4H-SiC. A modified Tersoff potential was used to model the interactions between the atoms. For cases where C and Si primary knockon atoms (PKAs) start parallel or antiparallel to the [0001] direction the threshold PKA energy for defect formation as well as the final defect configuration and its formation energy were determined. The elementary defects observed in 3C-SiC and 4H-SiC differ significantly whereas the corresponding threshold PKA energies and the formation energies of the configurations are mostly rather similar. In 4H-SiC new sites for C and Si interstitials were found: One site is situated between two C₃Si₃ hexagonal rings, the other between a C₃ and a Si₃ trigonal ring.