Dicarbon antisite defect in n-type 4H-SiC

概要

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We identify the negatively charged dicarbon antisite defect (C2 core at silicon site) in electron-irradiated n-type 4H-SiC by means of combined electron paramagnetic resonance (EPR) measurements and first-principles calculations. The HEI5 and HEI6 EPR centers (S=1/2; C1h symmetry) are associated with cubic and hexagonal dicarbon antisite defects, respectively. This assignment is based on a comparison of the measured and calculated hyperfine tensors of 13C and 29Si atoms as far as the second neighborhood around the defects. Theoretically, the dicarbon antisites are stable in a single negative charge state under a wide range of n-type samples. We found that the defects can be created under a wide range of irradiation conditions, and our measurements strongly suggest the existence of carbon antisite defects in the as-grown samples. Annealing studies revealed several atomistic processes such as recombination of carbon interstitials with vacancies and formation of carbon aggregates. These processes were activated at about 1000 °C, and as theoretically predicted, the dicarbon antisite is much more stable than the dicarbon interstitial defect (C2 core at carbon site). The measured activation temperature is consistent with the temperature range for forming various carbon aggregate-related photoluminescence centers.