The impact of reactor neutrons on 6H-SiC followed by irradiation of 91.3 MeV Xe ions–defects studies using positron annihilation spectroscopy

Abstract

The positron annihilation spectroscopy (PAS) was used to study the defects in 6H-SiC single crystal generated only by the impact of reactor neutrons and, it followed by the irradiation of a 91.3 MeV Xe ion beam. After neutron irradiation, only silicon vacancy-related defects, as identified by the Doppler broadening, are created. Further positron lifetime-based analysis showed that these defects are mainly (VC-VSi) divacancy, (VC-VSi)3 and (VC-VSi)4 clusters. With the post irradiation of a 91.3 MeV Xe ion beam, the defects generated at high neutrons dose remained almost similar, indicating saturation of positron trapping. The results indicate two competing annihilation processes for silicon monovacancy VSi- pre-saturation, where the VSi is annealed by aggregation to form (VC-VSi)n vacancy clusters, and a saturation, where the VSi is annealed by recombination with interstitials.