Positron annihilation spectroscopy investigation of vacancy defects in neutron-irradiated 3C-SiC

Abstract

Positron annihilation spectroscopy characterization results for neutron-irradiated 3C-SiC are described here, with a specific focus on explaining the size and character of vacancy clusters as a complement to the current understanding of the neutron irradiation response of 3C-SiC. Positron annihilation lifetime spectroscopy was used to capture the irradiation temperature and dose dependence of vacancy defects in 3C-SiC following neutron irradiation from 0.01 to 31 dpa in the temperature range from 380°C to 790°C. The neutral and negatively charged vacancy clusters were identified and quantified. The results suggest that the vacancy defects that were measured by positron annihilation spectroscopy technique contribute very little to the transient swelling of SiC. In addition, coincidence Doppler broadening measurement was used to investigate the chemical identity surrounding the positron trapping sites. It was found that silicon vacancy-related defects dominate in the studied materials and the production of the antisite defect CSi may result in an increase in the probability of positron annihilation with silicon core electrons.