High frequency H-diamond MISFET with output power density of 182 mW/mm at 10 GHz

RF power characteristics of hydrogen-terminated diamond metal-insulator-semiconductor field-effect transistors operating at 10 GHz have been reported, and an output power density of 182 mW/mm has been achieved. The diamond devices were fabricated by using a self-aligned process combined with 0.1 μm gate-length T-shaped gates. A high quality atomic layer deposition Al2O3 film with low leakage current was deposited as a gate dielectric by using H2O as the oxidant at a low temperature of 90 °C. The direct current output characteristics of the devices were measured by applying gate voltage in opposite directions, and a maximum drain current density of 741 mA/mm has been obtained. By small-signal measurements, the diamond device demonstrates a high extrinsic cutoff frequency fT of 66 GHz and a maximum frequency of oscillation fmax of 55 GHz.