Photoelectrochemical Function in Gate-Recessed AlGaN/GaN Metal–Oxide–Semiconductor High-Electron-Mobility Transistors

Photoelectrochemical (PEC) wet etching and oxidation methods were used for fabricating gate-recessed AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). The AlGaN layer was recessed by the PEC wet etching method. The PEC oxidation method was then performed to directly grow an oxide film on the recessed surface of the AlGaN layer as gate dielectric film and passivation of the surface. The gate-recessed AlGaN/GaN MOS-HEMTs exhibited a saturation drain-source current of 642 mA/mm at V_GS = 0 V, a maximum extrinsic transconductance of 86 mS/mm, and an off-state breakdown voltage of larger than -100 V.