Fabrication of depletion-mode GaAs MOSFET with a selective oxidation process by using metal as the mask

The n-channel depletion-mode GaAs MOSFETs with a selective liquid phase che mical-enhanced oxidation method at low temperature by using metal as the ma sk (M-SLPCEO) are demonstrated. The proposed process can simplify one mask to fabricate GaAs MOSFET and grow reliable gate oxide films as well as side -wall passivation layers at the same time. The 1 mum gate-length MOSFET wit h a gate oxide thickness of 35 nm shows the transconductance of 90 mS/mm an d the maximum drain current density larger than 350 mA/mm. In addition, a s hort-circuit current gain cutoff frequency f(T) of 6.5 GHz and a maximum os cillation frequency f(max) of 18.3 GHz have been achieved from the 1 mum x 100 mum GaAs MOSFET.