Neutrons and swift heavy ions irradiation induced damage in SiC single crystal

Abstract

Radiation damage induced in SiC single crystal by neutrons and sequentially neutrons + 91.3 MeV Xe ions irradiations were characterised by optical measurements (absorption and photoluminescence) and Raman spectroscopy. The samples were first irradiated with neutrons then followed by irradiation with 91.3 MeV Xe ions. Our aim is to check electronic ionization-induced pre-existing defects annealing in SiC single crystal. The data obtained for samples irradiated by neutrons were compared to those of neutrons + ions. It is found that neutrons irradiation induced absorption band at 780 nm and two emission bands at 550 nm and 920 nm. Both bands 780 nm and 920 nm assigned to silicon vacancy (VSi). Compared to neutrons irradiation, the same absorption and emission bands are observed for neutron + ions irradiated samples, indicating similar types of defects formation by additional 91.3 MeV Xe ions. The bands growth rapid at low dose followed by a saturation effect above a dose of 2.0 × 10−4 dpa for neutrons and 10.6 × 10−3 dpa for neutrons + ions. The stress follows the same dose-dependence as the absorption band, suggesting a good correlation between the stress and the silicon vacancies (VSi). Raman results proved that additional 91.3 MeV Xe ions irradiation induced the pre-existing damage annealing in SiC crystal. However, at high pre-existing defects concentration and Xe ions dose a competition between defects creation and annealing takes place. To confirm the results experiments using Doppler Broadened Emission Spectroscopy (DBS) using Variable Energy Slow Positron Beam, are planned for our next study.