Channel-recessed 4H-SiC MESFETs were fabricated and demonstrated excellent small signal characteristics. A saturated current of 250-270 mA/mm at V_(gs) = 0 V and a maximum transconductance of 40-45 mS/mm were measured for channel-recessed devices with a gate length of 0.45 m. The three-terminal breakdown voltages (V_(ds)) range from 120 V to 150 V. The F_t and F_(max) of the 2 * 200 m devices were measured to be 14.5 GHz and 40 GHz, respectively. The channel recess technique results in a lower saturation current but higher breakdown voltage which makes it possible for the devices to operate at high voltages. Si_3N_4 passivation suppresses the instability in DC characteristics and improves CW power performance by reducing the surface effects. Less dispersion in the drain current during a power sweep was observed after passivation.
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