Electric field modulation and hot-electron suppression in AlGaN/GaN HEMTs on Si using a hybrid p-NiO RESURF-FP termination

Abstract We report enhanced breakdown voltage ( V BR ) and reliability in AlGaN/GaN HEMTs on silicon substrates by employing a hybrid termination structure consisting of a p -type NiO reduced surface field (RESURF) layer and an extended NiO field plate (FP). The RESURF-FP hybrid structure modulates the lateral electric field via a dual mechanism: (1) charge-assisted depletion engineering by the p-NiO RESURF layer and (2) capacitive coupling effect by the gate-connected NiO FP, without introducing additional mobile charge carriers. Electrostatic simulations show that this dual-modulation strategy effectively suppresses lateral electric field peaks, shifts the peak field away from the gate edge, and reduces its field strength from 4 MV cm −1 to 3.1 MV cm −1 , thereby suppressing hot-carrier injection and interface degradation. As a result, the devices exhibit a 45% improvement in V BR while maintaining a high on-state current and a low specific on-resistance ( R on,sp ) of 3 mΩ cm 2 . Reliability characterization under gate pulse and high-temperature conditions show minimal threshold voltage shift (<0.1 V), confirming suppressed interface traps and improved device stability enabled by the etching-free regrown p-NiO gate and field-modulated termination design. These results demonstrate an effective strategy for electric field control and reliability enhancement in high-voltage GaN-on-Si HEMTs.