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

We report enhanced breakdown voltage (VBR) 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 field plate, 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 to 3.1 MV/cm, thereby suppressing hot-carrier injection and interface degradation. As a result, the devices exhibit a 45% improvement in VBR while maintaining a high on-state current and a low specific on-resistance (Ron,sp) of 3 mΩ·cm². Reliability characterization under gate pulse and high-temperature conditions show minima l 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-modula ted termination design. These results demonstrate an effective strategy for electric field control and reliability enhancement in high-voltage GaN-on-Si HEMTs.