Analysis and prediction of stability in commercial, 1200 V, 33A, 4H-SiC MOSFETs

State-of-the-art, commercially available, 4H-SiC MOSFETs are evaluated for stability under high-temperature over-voltage and pulsed over-current conditions. The devices show maximum vulnerability under high-temperature accumulation stress, demonstrating that the gate oxide is more prone to hole trapping than to electron trapping. The power MOSFET architecture coupled with a high interface trap density enables us to predict the stability of the device through a simple evaluation of the free-wheeling diode ideality factor (η) of the unstressed device. The pulsed over-current operation results in degradation similar to electron trapping at high temperature, presumably due to overheating of the device beyond its specified junction temperature. Over-current degradation is more severe at high switching frequency.