Polycrystalline diamond MESFETs by Au-mask technology for RF applications

Abstract

Metal-semiconductor field effect transistors (MESFETs) were fabricated on H-terminated polycrystalline diamond. The DC characteristics of the p-channel MESFET showed a maximum drain current density of 204 mA/mm at a gate-source voltage of −6 V, and a maximum transconductance of 20 mS/mm at a drain-source voltage of −1.5 V. The small signal S-parameters of MESFET with 2 × 100 μm gate width and 2 μm gate length were measured. An extrinsic cut-off frequency (fT) of 1.7 GHz and the maximum oscillation frequency (fmax) of 2.5 GHz were obtained, which was the first report on diamond MESFETs with RF characteristics in China.