Electrical Characteristics and Fast Neutron Response of Semi-Insulating Bulk Silicon Carbide

The electrical characteristics and fast neutron response of a High Temperature Chemical Vapour Deposition (HTCVD) grown semi-insulating bulk SiC wafer has been measured. Current-Voltage measurements demonstrated a low leakage current in the region of 10^-10 to 10^-12v A with a bulk resistivity of at least 10¹²-10¹³ Ω.cm. Alpha particle spectroscopy measurements demonstrated an electron charge collection efficiency of up to 90% with reasonable reproducibility of the acquired spectra. Evidence of (incident particle) rate dependent polarisation was seen following a constant applied bias combined with alpha irradiation over a period of time (order of tens of minutes). The ability of the wafer to detect fast neutrons was demonstrated and a comparison drawn with the MCNPX simulated response of a bulk SiC device. Comparing the MCNPX simulated response of a bulk SiC device to that of a silicon device suggests a superior ability to detect fast neutrons with an intrinsic efficiency 1.7 times that of silicon.