Investigation on Surge Current Capability of 4H-SiC Trench-Gate MOSFETs in Third Quadrant Under Various V GS Biases

In this work, third-quadrantI–Vcharacterization and surge current tests are carried out on SiC asymmetric-trench MOSFET (DUT A) and SiC double-trench MOSFET (DUT B) under various gate–source biases (VGS). The surge capability is found to be uninfluenced byVGSfor DUT A. However, it has a 71.4% increase whenVGSchanges from 0 to −5 V for DUT B. TheI–Vcharacteristics in the third quadrant are measured under variousVGS. It is found that the channel is open when the source–drain voltage is >2.5 V for DUT A and >1.5 V for DUT B atVGS =0V. High-temperature measurements are also conducted from 298 K to 448 K. WhenVGS =0V, the channel current takes up to 50% at 10-A source-to-drain current for DUT B, whereas only 10% for DUT A. This could lead to high current/heat density in the channel of DUT B. The transient resistance is also extracted from the surgeI–Vtrajectories, and it is higher for DUT B tested underVGS =0V, which will increase the dissipated surge energy. Finally, the failure mechanism is analyzed. For DUT A, aluminum melting contributes to the failure atVGS= -5V andVGS =0V. For DUT B tested atVGS =0V, the earlier breakdown happens due to gate oxide failure.