Anomalous dynamic on-resistance instability mechanisms of p-GaN gate AlGaN/GaN HEMTs under power cycling tests

In this study, the instability mechanisms of dynamic on-resistance (RDSON) of p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) were investigated under power cycling tests (PCTs). An anomalous dynamic RDSON instability behavior was observed, with an obvious decrease of 17.8% in the first stage (≤30k-cycle PCT), followed by a slight increase of 8.6%. The deep-level transient spectroscopy results show that the electron trap concentration in the AlGaN/GaN region and the hole trap concentration in the p-GaN layer decreased in the first stage, and then increased with increasing stress time. In addition, a new hole trap appeared in the AlGaN/GaN region after the 30k-cycle PCT. The decreased concentrations of the electron trap and hole trap below the gate increase the electrons in the two-dimensional electron gas in the first stage, reducing the dynamic RDSON. Afterward, the electron trapping enhances the depletion of the channel electrons and the increased hole trap concentration causes net negative charges under the gate, increasing the dynamic RDSON. This work provides important experimental evidence to understand the underlying mechanisms of the dynamic RDSON instability in p-GaN gate AlGaN/GaN HEMTs.