Performance of Silicon Carbide MOSFETs Under Gamma Radiation

Wide Bandgap (WBG) semiconductor devices based on Silicon Carbide (SiC) and Gallium Nitride (GaN) are recently considered attractive for high performance power electronics converters due to their high efficiency, high operating temperature and high switching frequency. The manufacturing processes for these WBG devices are evolving and have not still reached maturity levels leading to the generation of electrically active defects during long term operations. Such defect generation affects the reliability of operation in various environmental conditions. In this paper, we present a study of reliability of SiC power Metal–Oxide–Semiconductor Field Effect Transistor (MOSFETs) when operated under gamma radiation environment. Commercially available SiC MOSFETs rated at 900 V, 23 A were tested under Cobalt-60 gamma radiation at a dose rate 104 krad/h. The degradation of the device performance was investigated by measuring the Current–Voltage (I–V) characteristic prior to irradiation and post irradiation up to a total ionizing dose of 700 krads. No failure of the MOSFETs was observed up to the gamma dose of 700 krads. However, the threshold voltage of MOSFETs shifted in a negative direction which increased with total ionizing dose. Such threshold voltage shift could be a reliability concern as this could lead to undesired turn on of the device. The experimental details and results of gamma radiation induced degradation of SiC MOSFETs are presented in this paper.