Positron annihilation of vacancy-type defects in neutron-irradiated 4H-SiC
Abstract
Annealing behavior of vacancy-type defects in n-type 4H-SiC, which was irradiated with neutrons up to a dose of 3.2 × 10 21 m -2 ( E > 1 MeV) at 20 °C, was investigated by positron annihilation spectroscopy. Isochronal annealing results indicate that there are four different recovery stages in the irradiated 4H-SiC. In stage I, in the temperature range of 20-100 °C, the defect recovery is attributed to recombination between close vacancies and interstitials, and carbon and silicon clusters are formed by the migration of their interstitials. In stage II (200-1100 °C), carbon and silicon interstitials disappear at permanent sinks due to the long-range migration. Silicon and carbon vacancies move actively in stage III (1200-1400 °C). In stage IV (>1400 °C), more stable silicon vacancy complexes dissociate. Although, no vacancy-type defects are observed in 4H-SiC after annealing at 1600 °C, interstitial-type or anti-site defects are stable.
- Publication:
-
Journal of Nuclear Materials
- Pub Date:
- April 2009
- DOI:
- 10.1016/j.jnucmat.2008.12.326
- Bibcode:
- 2009JNuM..386..169X