Effect of recess length on DC and RF performance of gate-recessed AlGaN/GaN HEMTs

We present the effect of gate-recess length on DC and RF performance of AlGaN/GaN gate-recessed HEMTs. 0.15 μm gate-length AlGaN/GaN HEMTs with varying gate-recess lengths were fabricated. DC and microwave performance did not exhibit significant dependence on the gate-recess length. We attribute these results to essentially identical series source resistances, so that all the gate-recessed HEMTs exhibited similar DC and RF performance. This conclusion is derived from the fact that the values of ohmic contact resistances dominated over the values of channel resistances. The nature of the breakdown in the HEMTs was also studied. The results of temperature-dependent breakdown voltage measurements suggest that the breakdown mechanism was mainly due to tunneling gate leakage currents via shallow traps.