Enhanced surface passivation of AlGaN/GaN HEMTs via GaON-engineered interface for improved performance

In this study, we report a novel multi-step surface passivation scheme for AlGaN/GaN high electron mobility transistors, integrating oxygen plasma treatment followed by high-temperature annealing (OPANT), Wet Buffered Oxide Etch (BOE) wet etching, remote plasma pre-treatment, and a stacked plasma-enhanced atomic layer deposition Al2O3/plasma-enhanced chemical vapor deposition SiO2 dielectric layer. This approach effectively forms a crystalline GaON layer at the interface, enhancing lattice compatibility with the dielectric and significantly reducing interface trap density. The proposed passivation yields a device with superior electrical performance, including a subthreshold swing of 66 mV/dec, an ION/IOFF ratio over 109, three orders of magnitude reduction in gate leakage and off-state leakage, and improved dynamic RON behavior under high drain bias stress. Devices incorporating a GaON gate interlayer exhibit enhanced gate reliability.