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

In this work, third-quadrant $I$ – $V$ characterization 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 ( $V_{\mathrm {GS}}$ ). The surge capability is found to be uninfluenced by $V_{\mathrm {GS}}$ for DUT A. However, it has a 71.4% increase when $V_{\mathrm {GS}}$ changes from 0 to −5 V for DUT B. The $I$ – $V$ characteristics in the third quadrant are measured under various $V_{\mathrm {GS}}$ . 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 at $V_{\mathrm {GS}} =0$ V. High-temperature measurements are also conducted from 298 K to 448 K. When $V_{\mathrm {GS}} =0$ V, 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 surge $I$ – $V$ trajectories, and it is higher for DUT B tested under $V_{\mathrm {GS}} =0$ V, which will increase the dissipated surge energy. Finally, the failure mechanism is analyzed. For DUT A, aluminum melting contributes to the failure at $V_{\mathrm {GS}}= -5$ V and $V_{\mathrm {GS}} =0$ V. For DUT B tested at $V_{\mathrm {GS}} =0$ V, the earlier breakdown happens due to gate oxide failure.