RF Operation of Hydrogen-Terminated Diamond Field Effect Transistors: A Comparative Study

Three sets of different gate-length field-effect transistors (250, 120, and 50 nm) have been defined on homoepitaxial hydrogen-terminated diamond with the 50-nm device being the smallest gate length diamond transistor fabricated to date. DC- and small-signal RF measurements were undertaken to compare the operation of these gate nodes. RF small-signal equivalent circuits were generated to contrast individual components and better understand the operation at various gate dimensions. Scaling the gate length to smaller dimensions leads to an increase in the cutoff frequency of these devices although parasitic elements are found to dominate at the shortest gate length of 50 nm, limiting the outstanding potential of these devices.