Depletion-mode GaAs MOSFET with a low temperature selective grown oxide gate

A selective oxidation process by using metal as the mask is proposed to fabricate the n-channel depletion-mode GaAs MOSFET with liquid phase chemical-enhanced oxidation method at low temperature. Metals are deposited firstly for source and drain and then used as the mask for growing gate oxide and side-wall passivation, simultaneously. The proposed selective oxidation process can simplify one mask process to fabricate GaAs MOSFET and achieve more reliable oxide layers. The fabricated 2 mum gate-length GaAs MOSFET shows the transconductance larger than 75 mS/mm with a selective grown gate oxide thickness of 35 nm. In addition, the microwave characteristics of short-circuit current gain cutoff frequency f(T) and a maximum oscillation frequency f(max) have also been demonstrated, respectively.