4H-SiC MESFET with 65.7% power added efficiency at 850 MHz

4H-SiC MESFET's on conducting substrates were fabricated and characterized for large-signal performance over a wide range of gate and drain biases. At V/sub ds/=25 V the current density was 225 mA/mm and the peak f/sub max/ for these devices was 16 GHz. At V/sub ds/=50 V and I/sub dq/=50% I/sub dss/, the power density was 3.3 W/mm at 850 MHz. At V/sub ds/=40 V and I/sub dq/=5% I/sub dss/, the power added efficiency was 65.7%, which is the highest ever reported for a SiC MESFET. This is the first Class B data presented for a SiC MESFET.