True Breakdown Voltage and Overvoltage Margin of GaN Power HEMTs in Hard Switching

This work studies the dynamic breakdown voltage (BV) and overvoltage margin of a 650-V-rated commercial GaN power HEMT in hard switching. The dynamic BV measured in the hard switching circuits is over 1.4 kV, being 450 V higher than the static BV measured in the quasi-static I-V sweep. The device can survive at least 1 million hard-switching overvoltage pulses with 1.33 kV peak overvoltage (similar to 95% dynamic BV). Recoverable device parametric shifts are observed after the 1-million pulses, featuring small reductions in threshold voltage and on-resistance. These shifts are different from the ones after the hard-switching pulses without overvoltage and are attributable to the trapping of the holes produced in impact ionization. These results suggest that the BV and overvoltage margin of GaN HEMTs in practical power switching can be significantly underestimated using the static BV.

Automated summary

This study investigates the dynamic breakdown voltage and overvoltage margin of a 650-V-rated commercial GaN power HEMT in hard switching. It was found that the dynamic BV of the device is significantly higher than the static BV, and the overvoltage margin is also underestimated when using the static BV for estimation. The device showed resilience to 1 million hard-switching overvoltage pulses with recoverable parametric shifts.