Impact of metal/oxide interface on DC and RF performance of depletion-mode GaAs MOSFET employing MBE grown Ga 2O 3(Gd 2O 3) as gate dielectric

Abstract

Employing Ga 2O 3(Gd 2O 3) as gate dielectric and Si-doped GaAs as conducting channel, depletion-mode GaAs MOSFETs were fabricated. DC I– V and transfer curves show no pinch-off and drain current hysteresis. Etching a thin layer from the top of Ga 2O 3(Gd 2O 3) in the gate region before gate metal deposition leads to full pinch-off and significantly reduces the drain current hysteresis. This process may remove the contaminated Ga 2O 3(Gd 2O 3) due to exposure to chemicals and prior processes, and thus results in a clean gate metal to oxide interface. The clean gate metal to Ga 2O 3(Gd 2O 3) interface also leads to higher DC transconductance, higher unity current gain cut-off frequency as well as higher unity power gain cut-off frequency as compared with GaAs MOSFET devices with a contaminated metal/oxide interface at the gate.