Microwave operation of diamond metal-insulator-semiconductor field-effect transistors fabricated on single-crystal chemical vapor deposition substrate

Diamond metal-insulator-semiconductor field-effect transistors (MISFETs) were fabricated on single-crystal diamond films, and small- and large-signal RF operations were evaluated. This is the first report on large-signal RF operation for diamond MISFETs, and the RF power density was 2.14 W/mm at 1 GHz. This value is comparable to those of GaAs FETs and Si lateral-diffusion metal-oxide-semiconductor field-effect transistors (LDMOSFETs). Also, for single-crystal diamond MISFETs, the highest cutoff frequency (f_T) of 30 GHz was obtained in 0.3-μm-gate-length (L_G) MISFET. The carrier velocity, which is extracted from the relationship between f_T and L_G, reached 6×10⁶ cm/s.