AlGaAs/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor with low temperature liquid phase deposited Al₂O₃ gate insulator

AlGaAs/InGaAs/GaAs metal-oxide-semiconductor–pseudomorphic high electron mobility transistors (MOS-PHEMTs) with Al₂O₃ as a gate dielectric oxide prepared in low-temperature liquid phase deposition (LPD) are presented in this study. The Al₂O₃ films on the GaAs substrates are characterized by means of x-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. The applications to depletion mode n-channel GaAs MOS-PHEMTs showed larger gate swing voltage, lower gate leakage current, higher breakdown voltage, higher drain current density, and maximum extrinsic transconductance compared to conventional AlGaAs/InGaAs PHEMTs. This demonstrates that LPD Al₂O₃ could be a suitable candidate for future gate insulator applications.