High performance recessed gate AlGaN/GaN HEMTs

Recessed gate AlGaN/GaN HEMTs are fabricated using a low damage dry-etching method, where the device threshold voltage shifts from -7 V to -2 V, depending on the recess depth. A maximum drain current density of 1.5 A/mm was achieved at gate-source voltage of 4 V. For recessed gate devices with 1 mum gate length, peak intrinsic transconductance of 600 mS/mm was obtained. Small-signal S-parameter measurements showed f(max), approaching 44 GHz with a gain of 13 dB at 8 GHz. At 8 GHz, saturated power density of 4 W/mm was obtained. Long term stable RF power operation was evaluated at different RF input/output power level. At 65 % of the saturated power level, no noticeable reduction in output power and gain is observed for over 60 hrs.