EFFECTS OF 3.0 MeV ELECTRON IRRADIATION ON 4H-SiC WAFER PROPERTIES
Effects of 3 MeV electron (10 mA) irradiation at room temperature on the phase, microstructure, electrical and life time properties of 4H-SiC wafer were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), four point probe current-voltage measurements and positron annihilation spectroscopy. It was found that irradiation damage in SiC wafer is significantly increased with the increase of radiation dose as observed in SEM. Irradiation also resulted in modification of crystallite size as identified by XRD. The resistance of a sample before irradiation was found to be 0.8 MΩ, whereas for a sample irradiated at 200 kGy, the resistance as measured by four point probe was 5.2 MΩ. It seems that the increase of resistance hence, reduction in conductivities could be due to defects induced by the radiation dose received then created leakage currents at both reverse and low-forward biases and creation of traps in the SiC. Meanwhile positron annihilation spectroscopy (PAS) was used to analyse the life time of irradiated samples which nonetheless shows that all irradiated sample have similar life time of 151 ps. It was observed that that no degradation process of materials experienced by SiC wafer irradiated at 500 kGy.