RF characteristic of MESFET on H-terminated DC arc jet CVD diamond film

Diamond has been considered to be a potential material for high-frequency and high-power electronic devices due to the excellent electrical properties. In this paper, we reported the radio frequency (RF) characteristic of metal-semiconductor field effect transistor (MESFET) on polycrystalline diamond films prepared by direct current (DC) arc jet chemical vapor deposition (CVD). First, 4 in polycrystalline diamond films were deposited by DC arc jet CVD in gas recycling mode with the deposition rate of 14 μm/h. Then the polished diamond films were treated by microwave hydrogen plasma and the 0.2 μm-gate-length MESFET was fabricated by using Au mask photolithography and electron beam (EB) lithography. The surface conductivity of the H-terminated diamond film and DC and RF performances of the MESFET were characterized. The results demonstrate that, the carrier mobility of 24.6 cm2/V s and the carrier density of 1.096 × 1013 cm−2 are obtained on the surface of H-terminated diamond film. The FET shows the maximum transition frequency (fT) of 5 GHz and the maximum oscillation frequency (fmax) of 6 GHz at VGS = −0.5 V and VDS = −8 V, which indicates that H-terminated DC arc jet CVD polycrystalline diamond is suitable for the development of high frequency devices.