Effects of Neutron Irradiation on the Static and Switching Characteristics of High-Voltage 4H-SiC p-type Gate Turn-off Thyristors

Abstract

Silicon carbide (SiC) has shown substantial promise in the fabrication of high-power devices, and SiC Schottky diodes and field-effect transistors (FETs) have been considered as potential candidates for outerspace and sensors applications. Due to the multipolar structure, SiC gate turn-off thyristor (GTO) device is relatively sensitive to the irradiation-induced point defects. However, how SiC GTO devices perform under neutron irradiation still needs to be clarified. In this paper, the effects of neutron irradiation on the static and dynamic switch characteristics of high-voltage 4H-SiC GTOs are investigated for the first time. For the static electrical properties, it is found that the forward current significantly decreases with the increasing neutron irradiation fluence. While the cathode leakage current in the blocking characteristics shows an insignificant change up to a neutron fluence of ${1.0} \times {10}^{{13}}$ n/cm2. For the switching characteristics, both the pulse peak current and di/dt show substantial reduction as the neutron fluence increases while the delay time increases after irradiation. The degraded performance of the static and dynamic characteristics of SiC GTO devices was then analyzed and attributed to the weakened conductivity modulation and reduced carrier injection efficiency into the drift layer. These two aspects originate from the significantly reduced carrier lifetime and deteriorated forward characteristics of anode-gate diodes, respectively.