Annealing behaviour of vacancy-type defects in n-type 4H–SiC, which was

irradiated with neutrons up to a dose of 3.2 x 1021/m2 (E>1MeV) at 20C, was

investigated by positron annihilation spectroscopy. Isochronal annealing results

indicate that there were four different recovery stages in the irradiated 4H–SiC. In

stage I, at 20 to 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 to 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 to 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