Temperature-dependent reverse-bias stress of normally-off GaN power FETs

•We have reverse-bias stressed normally-off power GaN FETs in the range 250-350 K.•The failure voltage does not show clear temperature dependence.•There is some correlation between failure voltage and the initial leakage current.•Deep gate-drain leakage path may be responsible for fatal failure.

We show results of temperature-dependent reverse-bias step-stressing of normally-off high-power GaN FETs. In the range 250–350 K, the stress voltage at which the FETs fail catastrophically does not show a clear temperature dependence, while some correlation is observed with the initial leakage current value. Our results, consistent with other published reports, point to the activation of a deep gate-to-drain leakage path as the responsible for fatal device degradation at large values of the drain–gate reverse bias.