A high-current pseudomorphic AlGaAs/InGaAs double quantum-well MODFET

Double quantum-well modulation-doped field-effect transistors (MODFETs) with planar-doped lattice-strained AlGaAs/InGaAs structure have been fabricated and characterized at DC and microwave frequencies. At 300 K the 0.3- mu m gate devices show a full channel current of 1100 mA/mm with a constant extrinsic transconductance of 350 mS/mm over a broad gate voltage range of 1.6 V. Excellent microwave performance is also achieved with a maximum available gain cutoff frequency f/sub mag/ of 110 GHz and a current gain cutoff frequency f/sub r/ of 52 GHz. A maximum output power of 0.7 W/mm with 30% efficiency is obtained at 18 GHz. >