fmax of 490 GHz metamorphic In0.52Al0.48As/In0.53Ga0.47As HEMTs on GaAs substrate

Metamorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As HEMTs on GaAs substrate with 60 nm gate length have been fabricated. Drain-to-source current I/sub ds/ of 600 mA/mm and extrinsic transconductance of 850 mS/mm were obtained with these devices. The cutoff frequency f/sub T/ of extrinsic current gain |h/sub 21/|/sup 2/ and maximum oscillation frequency f/sub max/ deduced from Mason's unilateral gain are 260 GHz and 490 GHz respectively. To the authors' knowledge, this frequency performance is the highest ever reported for HEMTs on GaAs substrate.