Analysis of bipolar degradation of 1200 V SiC power MOSFETs under high DC current stress

Abstract Currently, research on bipolar degradation in silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) focuses on devices rated above 1700 V, which exhibit severe bipolar degradation, while studies on 1200 V devices remain limited. In this work, the bipolar degradation is found in the 1200 V SiC MOSFETs under high direct current (DC) stress. In the experiment, two different SiC MOSFETs are subjected to high reverse DC stress at a case temperature of 80 °C, which is the minimum controllable temperature. After long-term current stress to the body diode, the devices’ on-resistance ( R on ) and their body diode forward voltage ( V SD ) exhibit a slight increase, which may be attributed to the formation and expansion of stacking faults (SFs). SFs impede the flow of majority carriers, significantly affecting carrier lifetime, leading to the increase in R on and V SD . Additionally, SFs may also provide a path for reverse bias leakage current, leading to a substantial rise in leakage current and a reduction in the device’s blocking capability, which is related to the epitaxial layer process of the device. Furthermore, the impact of temperature on bipolar degradation is also investigated. At the high temperature, the high-temperature gate bias stress leads to contrary degradation phenomena, masking bipolar degradation. The relevant results contribute to testing and verifying the long-term reliability of SiC MOSFET devices.