Influence of the Gate Switching Instability Induced Threshold Voltage Drift on the Hard Switching Behavior of 1.2 kV SiC MOSFETs

Silicon carbide MOSFETs have been tested under gate switching stress conditions with an operation frequency of 1.0 MHz until 10¹² cycles. The resulting threshold voltage drift was described by a power law and saturation effects have been observed for two out of three manufacturers. Further, the impact of the threshold voltage drift on switching transients was examined in double pulse tests and the resulting switching losses have been calculated. For one manufacturer the threshold voltage increased by almost 120 %, elevating the total switching losses by approximately 8 %. Due to the higher threshold voltage, resulting from gate switching stress, turn-on events were decelerated, whereas turn-off evens accelerated for all observed manufacturers.