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

摘要

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_2O3) 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.