Positron annihilation spectroscopy investigation of vacancy defects in neutron-irradiated3C-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 $380{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ to $790{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$. 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 ${\mathrm{C}}_{\mathrm{Si}}$ may result in an increase in the probability of positron annihilation with silicon core electrons.