The origin of dynamic on-resistance instability in GaN hybrid drain-gate injection transistors under hard-switching conditions

In this work, we investigate the origin of the dynamic on-resistance (RDSON) instability in GaN hybrid drain-embedded gate injection transistors under hard-switching conditions. Double-pulse tests reveal that the gate transient pulse voltage not only increases with increasing the turn-on time but also shows a non-monotonic dependence on drain voltage. Correspondingly, the dynamic RDSON initially increases, reaching a maximum at ∼200 V, then decreases at higher drain voltages. Based on in situ drain voltage transient measurements, three traps (DP1–DP3) were identified by extracting the time constant spectroscopy. DP1 is located in the bulk GaN or AlGaN buffer layer and shows negligible influence on dynamic RDSON. While DP2 and DP3 are related to interface states at the AlGaN/GaN heterojunction, which is further confirmed by deep-level transient spectroscopy with a high interface state density on the order of ∼1011 cm−2 eV−1. The results further confirm that the dynamic RDSON instability is attributed to the competition between electron trapping at these interface states and drain-initiated hole injection. These findings provide new insights into the trap-mediated dynamic performance of GaN-based high-electron-mobility transistors.