Reliability of hybrid-drain-embedded gate injection transistor

Reliability tests on 600V-rated GaN-based normally-off hybrid-drain-embedded Gate Injection Transistor (HD-GIT) are performed. High-temperature reverse-bias test on HD-GIT reveals that the lifetime is dependent on the leakage current before the reliability test. Acceleration factors for the temperature and reverse bias voltage are extracted. Based on the obtained results, devices are designed so that their lifetimes under V
_DS
= 480V (80% de-rated) at 80°C are longer than 1000 years, which are long enough for most conventional power converter applications. Dynamic high-temperature operation life test is also performed, under which their DC characteristics are within their normal range up to 3600h. In addition, HD-GITs are within their normal range under the similar reliability tests as applied for Si-based power transistors. The physical mechanisms for the reliability of HD-GIT are discussed. We conclude that the OFF-state reliability is explained by the so-called percolation degradation model, and that the hole injection from the p-type GaN embedded in the drain plays an important role to suppress the degradation under hard-switching operation test.