A Review of the Effects of Fast-Neutron Irradiation on the Performance of 4H-SiC Schottky Barrier Detectors

Silicon carbide (SiC) semiconductor radiation detectors are finding increasing applications in challenging nuclear radiation environments. These applications often involve elevated temperatures in addition to the inherent potential for high doses of ionizing radiation and the concomitant accumulation of radiation-induced damage. The wide bandgap of SiC allows operation at temperatures up to
$700~^{\circ }$
C and probably higher. Conventional low-band-gap semiconductors, such as silicon and germanium, cannot operate at elevated temperatures as a result of the interference of thermally generated charge carriers with the detection of those produced by nuclear events. Also, radiation damage will generally limit the performance of conventional low-bandgap semiconductors more than for SiC because the defects produced by radiation damage can operate more efficiently as charge generation centers and result in increased leakage current in low-band-gap devices; nevertheless, SiC radiation detectors will be limited by the accumulation of radiation damage. Many investigators have studied the effects of radiation exposure on the performance of SiC detectors, and we will review the results with an emphasis on the effects of neutron exposure on 4H-SiC Schottky-barrier neutron detectors. The effects of fast-neutron (
$E \gt 1$
MeV) at low fluences (
$\lt 10^{12}$
cm2) and higher fluences (up to
$10^{17}$
cm2) are summarized in terms of correlations and modeling of the response data. The effects of irradiation temperature on the accumulation of radiation damage are also discussed.