Photoelectrochemical oxidation-treated AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors with oxidized layer/Ta₂O ₅/Al₂O₃ gate dielectric stack

Photoelectrochemical (PEC) oxidation method was used to directly oxidize AlGaN layer as the oxide layer of AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMTs). High-k Ta₂O ₅ layer and wide bandgap Al₂O₃ layer were sequentially deposited on the PEC-oxidized layer as the gate dielectric stack of the MOS-HEMTs. Comparing with the Al₂O₃/Ta ₂O₅/Al₂O₃ gate dielectric stack, the resulting MOS-HEMTs exhibited improved performances, including a maximum extrinsic transconductance of 134 mS/mm, a Hooge's coefficient of 1.32 × 10^-4, and a maximum output power of 3.44 W/mm. These experimental results verified that high performance gate dielectric stack/AlGaN interface was achieved using the PEC oxidation method.