Surface-oxide-controlled InGaAs/InAlAs inverted-type metal-oxide-semiconductor high electron mobility transistors for sub-THz high-power amplifiers

Abstract Herein, we successfully improved the maximum oscillation frequency and maximum stable gain (MSG) across a wide bias range of surface-oxide-controlled (SOC) InGaAs/InAlAs inverted-type metal-oxide-semiconductor high-electron-mobility transistors (inverted MOS-HEMTs) by reducing the gate leakage current and drain conductance ( g d ). H 2 O vapor treatment selectively decreased the narrow band gap indium oxide at the surface of the In-based epitaxial layer via the SOC process before the gate oxide deposition. Furthermore, the calculation of band profiles indicated that the g d reduction was possibly attributed to the suppression of impact ionization in the InGaAs channel by inverted MOS-HEMTs. Consequently, SOC-inverted MOS-HEMTs demonstrated a high MSG of >12 dB at 100 GHz across a wide bias range.