Self-aligned pseudomorphic HEMT with a low-temperature-grown GaAs gate insulator

A new enhancement-mode GaAs pseudomorphic high-electron-mobility transistor (pHEMT) with a low-temperature-grown (LTG) GaAs gate insulator has been developed. The source and drain are doped by self-aligned implant and no gate recess is needed. The LTG-GaAs gate insulator drastically reduces the gate leakage current, allowing a maximum drain current of 390 mA/mm obtained at 3 V of forward gate bias. The maximum transconductance is 330 mS/mm and the cutoff frequency is 31 GHz for pHEMTs with a 0.5 µm gate length.