Abstract: AlGaN/GaN HEMTs at the X band based on homemade SiC substrates and homemade epi-layers are first reported.A 0.35μm gate length,1mm gate width microwave power device is produced with a gate-connected field plate.The power device exhibits a maximum drain current density as high as 0.83A/mm and a peak extrinsic transconductance of 236mS/mm.A unity current gain cutoff frequency(fT) of 30GHz and a power gain cutoff frequency of 31GHz are obtained.The device biased at a drain voltage of 40V demonstrates a continuous wave saturated output power of 8W with a gain of 4.9dB and a power-added efficiency of 45% at 8GHz.

Key words: AlGaN/GaN, HEMT, microwave power, gate-connected field plate