GaN/AlGaN HEMTs operating at 20 GHz withcontinuous-wave power density > 6 W/mm

MBE-grown GAN/AlGaN HEMTs have been fabricated on a 2" SiC wafer, where the source-drain spacing was 2 µm and the gate length was 0.15 µm. A peak extrinsic transconductance of 350 mS/mm and a maximum drain current density greater than 1.5 A/mm were obtained. Small-signal S-parameter measurement showed fT of 85 GHz and fMAX approaching 140 GHz. At 20 GHz, a continuous-wave output power density of 6.6 W/mm was obtained with power-added-efficiency (PAE) of 35%, yielding the highest reported power performance at 20 GHz.