Silicon carbide PIN diode detectors used in harsh neutron irradiation

Silicon carbide (SiC) neutron detectors based on PIN diode with Ti/Au electrode structure have been successfully developed and considered to be a good option for neutron detection related to harsh radiation environment, but these detectors suffered inevitable irradiation damage and performance degradation, ultimately damaged the applications severely. Unfortunately, the systematic research focusing on the degradation and irradiation defects is lack, and the mechanism of degradation is not clear yet. In this paper, these issues are carefully studied: SiC detectors were irradiated by neutrons emitted from fusion neutron generator and nuclear reactor with fluence ranging from 1 × 10¹⁴ n/cm² to 2 × 10¹⁶ n/cm², then the performance degradation and neutron induced defects were carefully investigated. It is concluded that the SiC detectors could endure neutron irradiation as least 10¹⁶ n/cm². Although neutron irradiation could induce breakdown of PN junction, decrease of charge collection efficiency and worsening of energy resolution, all the detectors are still alive; furthermore, they could still acquire integrated response spectra to alpha particles with neglectable increase of dark current at neutron fluence of 2 × 10¹⁶ n/cm². The di-carbon antisite defects and vacancy-type defects induced by neutron irradiation should be responsible for the performance degradation, according to low temperature photoluminescence and positron annihilation Doppler broadening measurements. Possible degradation mechanism was discussed as well.