High efficiency microwave power AlGaAs/InGaAs PHEMTs fabricated by dry etch single gate recess

An optimized pseudomorphic high electron mobility transistor (PHEMT) epitaxial structure processed with a novel single gate recess technique is shown to achieve 850 mW of output power (760 mW/spl middot/mm/sup -1/ saturated power density) with 50% power added efficiency at X-band when operated at a CW and nearly class A condition. The multi-finger devices (14/spl times/80 /spl mu/m) retain high extrinsic transconductances (380-420 mS/spl middot/mm/sup -1/), with exceptional breakdown voltage (>18 V). The combination of optimized epi layer structure design and uniform gate recess using a damage-free, etch-stop, dry plasma processing step produces consistently and uniformly high f/sub T/ values (80 GHz at V/sub DS/=1 V, 35 GHz at V/sub DS/=7 V) even at low I/sub DS/ (100 mA/spl middot/mm/sup -1/).< >