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//m//a//g of 110 GHz and a current gain cutoff frequency f//r of 52 GHz. A maximum output power of 0. 7 W/mm with 30% efficiency is obtained at 18 GHz.