Investigations on the Degradation of Different Gate Oxide Regions of SiC MOSFET Under Different Repetitive DC Bus Voltage

Due to the exceptional electrothermal properties, SiC MOSFET is considered as one of the most potential candidates in power devices. However, the short circuit reliability of SiC MOSFET is the weak point. In this paper, the degradation of different gate oxide regions of 1.2kV SiC MOSFET under different repetitive short-circuit DC bus voltage is investigated. A short-circuit test system is built, which applied repetitive short-circuit stress on the SiC MOSFET. Capacitance-Voltage curves of the devices after the short-circuit tests were extracted by power device analyzer and were used for gate degradation extraction. The degradation of SiC MOSFET channel region and JFET region under the condition of DC bus voltage of 200V, 400V and 600V was studied. Under same SC energy, the degradation of the JFET region of the device becomes serious under high voltage conditions, while the degradation of the channel region is basically not affected by the DC bus voltage. Finally, the electrothermal stress of different gate oxide regions during the short circuit process is analyzed by Sentaurus TCAD simulation, which is helpful to analyze its degradation mechanism.