Positive identification, by low-temperature photoluminescence micro-spectroscopy, of the 2 spin states of the di-C antisites in 4H-SiC was considered. The defects were created by high-dose electron irradiation at room temperature or by subsequent exposure to intense 325nm radiation at up to 1300C. Identification was achieved by their formation and annealing characteristics, by the energies of their local vibrational modes, by the nature of their splitting in 13C isotope enriched samples, and by comparison with published results of ab initio local density approximation calculations. Four related but different forms of this defect were predicted, two with S=0 and two with S=1, and their calculated properties were consistent with the experimental results presented here. The excitation processes for the optical centers within the irradiated region were quite unusual. For a 488nm laser excitation, both spin states of the defect were observed by up-conversion. For a 325nm excitation, the optical centers were only observed at the periphery of the high-dose irradiated regions after the sample was exposed to an intense 325nm beam. In this case, the optical centers were mainly in the S=0 state. The centers were eliminated by annealing in the range of 800 to 950C.

Creation and Identification of the Two Spin States of Dicarbon Antisite Defects in 4H-SiC. J.W.Steeds, W.Sullivan, S.A.Furkert, G.A.Evans, P.J.Wellmann: Physical Review B, 2008, 77[19], 195203 (11pp)