AbstractThe commercialization of 4H-SiC MOSFETs will greatly depend on the reliability of gate oxide. Long-term gate oxide reliability and device stability of 1200 V 4H-SiC MOSFETs are being studied, both under the on- and off-states. Device reliability is studied by stressing the device under three conditions: (a) Gate stress - a constant gate voltage of +15 V is applied to the gate at a temperature of 175°C. The forward I-V characteristics and threshold voltage are monitored for device stability, (b) Forward current stress – devices are stressed under a constant drain current of Id = 4 A and Vg = 20 V. The devices were allowed to self-heat to a temperature of Tsink = 125°C and the I-V curves are monitored with time, and (c) High temperature reverse bias testing at 1200 V and 175°C to study the reliability of the devices in the off-state. Our very first measurements on (a) and (b) show very little variation between the pre-stress and post-stress I-V characteristics and threshold voltage up to 1000 hrs of operation at 175°C indicating excellent stability of the MOSFETs in the on-state. In addition, high temperature reverse bias stress test looks very promising with the devices showing very little variation in the reverse leakage current with time.
Understanding the role of threading dislocations on 4H-SiC MOSFET breakdown under high temperature reverse bias stress