Investigation on Surge Current Capability of 4H-SiC Trench-Gate MOSFETs in Third Quadrant Under Various VGS 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.