High performance fully selective double recess InAlAs/InGaAs/InP HEMTs

InP HEMTs with a double recess 0.12 μm gate have been developed. The material structure was designed to be fully selective etched at both recess steps for improved uniformity and yield across the whole wafer. Devices demonstrated DC characteristics of extrinsic transconductances of 1000 mS/mm, maximum current density of 800 mA/mm and gate-drain reverse breakdown voltages of -7.8 V. Power measurements were performed at both 20 GHz and 60 GHz. At 20 GHz, the 6×75 μm devices yielded 65% maximum power added efficiency (PAE) with associated gain of 13.5 dB and output power of 185 mW/mm. When tuned for maximum output power it gave an output power density of 670 mW/mm with 15.6 dB gain and 49% PAE. At 60 GHz, maximum PAE of 30% has been measured with associated output power density of 290 mW/mm and gain of 7.4 dB. This represents the best power performance reported for InP-based double recess HEMT's.