650 mW/mm output power density of H‐terminated polycrystalline diamond MISFET at 10 GHz

In this work, metal–insulator–semiconductor field effect transistors (MISFET) with gate length of 350 nm were fabricated on hydrogen‐terminated polycrystalline diamond by a self‐aligned process. Aluminium film with thickness of 2 nm was evaporated on the sample and formed self‐oxidised alumina to act as the gate dielectric. The devices show good direct current and radio frequency performances with a maximum frequency of oscillation ( f max ) of 34 GHz and continuous‐wave output power density of 650 mW/mm at 10 GHz.