Development of Radiation Detectors Based on Semi-Insulating Silicon Carbide

Fast-neutron detectors based on high-purity semi-insulating 4H silicon carbide (SiC) semiconductor have been fabricated and tested. The response characteristics of these detectors have been compared with those of epitaxial 4H-SiC Schottky diode detectors. The charge collection efficiency has been tested using alpha particles and the fast-neutron response has been tested with 14-MeV and 2.5-MeV neutrons. Over the applied voltage range tested, the charge collection efficiency for alpha particles is generally lower for the semi-insulating SiC detectors, and the fast-neutron detection efficiencies are also lower. Both the lower charge collection efficiency and the lower fast-neutron detection efficiencies are primarily caused by charge recombination in combination with the low electric fields across the thicker semi-insulating SiC detectors and the inability of the detector packaging to adequately withstand high voltages. Semi-insulating SiC detectors provide a viable alternative to epitaxial SiC diode detectors for fast-neutron detection and methods to improve the performance of semi-insulating SiC detectors are proposed.