Annealing behaviour of vacancy-type defects in n-type 4H–SiC, which was irradiated with neutrons up to a dose of 3.2 x 1021m−2 (E>1MeV) at 20C, was investigated by positron annihilation spectroscopy. Isochronal annealing results indicated that there were four different recovery stages in the irradiated 4H–SiC. In stage I, in the temperature range of 20–100C, the defect recovery was attributed to recombination between close vacancies and interstitials, and carbon and silicon clusters were formed by the migration of their interstitials. In stage II (200–1100C), carbon and silicon interstitials disappeared at permanent sinks due to the long-range migration. Silicon and carbon vacancies move actively in stage III (1200–1400C). In stage IV (>1400C), more stable silicon vacancy complexes dissociate. Although, no vacancy-type defects were observed in 4H–SiC after annealing at 1600C, interstitial-type or anti-site defects were stable.

Positron Annihilation of Vacancy-Type Defects in Neutron-Irradiated 4H–SiC. Q.Xu, T.Yoshiie, M.Okada: Journal of Nuclear Materials, 2009, 386-388, 169-72