Performance Enhancement of Al 2 O 3 /H-Diamond MOSFETs Utilizing Vacuum Annealing and V 2 O 5 as a Surface Electron Acceptor

We report on the performance enhancement of 250-nm gate-length H-diamond FETs through thermal treatment of devices at 400 °C and the incorporation of V 2 O 5 as a surface electron acceptor layer. Encapsulation of the H-diamond surface with V 2 O 5 is found to increase the transfer doping efficiency and reduce the device access resistance. A reduction in ohmic contact resistance and channel resistance beneath the gate after thermal treatment at 400 °C was found to further reduce the device ON-resistance and increase the maximum drain current and peak transconductance. These devices demonstrate the highest drain current (375 mA/mm) and transconductance (98 mS/mm), yet reported for H-diamond FETs of this gate length that incorporate an electron acceptor oxide layer.