A rich variety of optical centers with high energy local vibrational modes was found in electron-irradiated 4H-SiC in both the as-irradiated and annealed states. These energies were measured and the annealing dependence of the optical centers was investigated by low-temperature photoluminescence spectroscopy. In view of the relatively high energies of these modes, it was anticipated that they involve carbon interstitials and a detailed correlation has therefore been undertaken, in selected cases, between the experimentally observed energies and those calculated by recent local density approximation, i.e., ab initio methods for atomic arrangements involving carbon interstitials. When satisfactory agreement was achieved, the annealing behavior was compared to the calculated stabilities of the defects concerned. As a result, different configurations of carbon antisite defects were identified together with their spatial distributions with respect to the irradiated areas and their sequences of appearance and disappearance on annealing. These findings significantly add to the understanding of the radiation damage process and its subsequent development and recovery on annealing. Some of the optical centers that have well-defined local vibrational modes remain to be identified in the future.

Identification of Antisite Carbon Split-Interstitial Defects in 4H-SiC. J.W.Steeds, W.Sullivan: Physical Review B, 2008, 77[19], 195204 (9pp)