This work presents GaN-on-Si metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) featuring a quaternary InAlGaN barrier and gate field plate (GFP) for power device applications. The proposed device has achieved a 40% increase in drain current and a 21.6% lower ON-resistance (R \(_{ON}\) ) compared to conventional AlGaN/GaN HEMTs, due to a high carrier density of \(\sim\) 1.9 \(\times 10^{13}\text{cm}^{-2},\) high mobility of 1540 \(\text{cm}^{2}\) /V·s. These enhancements yield a low specific ON-resistance (R \(_{ON,sp}\) ) of 2.27 m \(\Omega\) \(\cdot\) cm \(^{2}\) . The device also exhibits excellent breakdown performance, with a drain breakdown voltage of \(\sim\) 950 V without Gate Field Plate (GFP) and >1500 V with GFP optimized at 4 \(\mu\) m, enabled by a low sheet resistance (R \(_{sh}\) ) of \(\sim\) 215 \(\Omega\) / \(\square\) . Furthermore, thermal reliability is confirmed by a minimal threshold voltage (V \(_{TH}\) ) of \(\sim\) 0.4 V and a variation of approximately 20% in maximum drain current (I \(_{D,max}\) ) at 150 \(^{\circ }\) C. Moreover, this study attains a state-of-the-art achievement with a tradeoff of a high device figure-of-merit (FOM) on BV \(_{DS}^{2}\) /R \(_{ON, sp}\) of \(\sim\) 1100 MW/cm \(^{2}\) . In addition, we have also carried out the Long-term reliability under positive and negative bias temperature instability (PBTI/NBTI) stress tests under the specific bias of V \(_{GS}\) =10 V, V \(_{DS}\) =0 V and V \(_{GS}\) = -30 V, V \(_{DS}\) =0 V, respectively. It reveals that all GFP-equipped devices exhibit smaller V \(_{TH}\) shifts under PBTI, while NBTI induces a slightly higher degradation, indicating distinct charge-trapping mechanisms in both processes.
