Breakdown behaviour of high-voltage GaN-HEMTs

The breakdown mechanism of high-voltage GaN-HEMT was analysed using the experimental I-V characteristics and two-dimensional device simulation results. The holes are generated by the impact ionization under high applied voltage. A part of the generated holes accumulates beneath the gate and lowers the gate potential barrier. As a result, the source leakage current flowing over the gate potential increases rapidly and breakdown occurs. From these results, suppression of the impact ionization and the hole remove structure are effective for a highly reliable design concerning the breakdown.