Accurate Evaluation of Threshold Voltage Hysteresis in SiC MOSFET under Switching Stress

In this letter, a novel method is proposed for accurately evaluating the transient recoverable threshold voltage (Vth) shift of SiC MOSFET caused by hysteresis effect. Based on a resistive load circuit with multistage gate drive module, the method achieves a fast switching from high-frequency bipolar switching gate bias stress to Vth acquisition. Furthermore, the method is experimentally verified with a 1200 V commercial SiC MOSFET. The Vth shift is evaluated after bipolar switching stress, and the time interval between stress and measurement, i.e., the test delay is reduced to 100 ns. In addition, Vth shift with different test delays after 500 kHz bipolar stress is evaluated. The results demonstrate that the positive and negative Vth shift measured after a delay time of 1 μs can be underestimated by more than 32% and 22% when compared to a shorter test delay of 100 ns