f max of 490 GHz metamorphic In 0.52 Al 0.48 As/In 0.53 Ga 0.47 As HEMTs on GaAs substrate

Metamorphic In0.52Al0.48As/In0.53Ga0.47As HEMTs on GaAs substrate with 60 nm gate length have been fabricated. Drain-to-source current Ids of 600 mA/mm and extrinsic transconductance of 850 mS/mm were obtained with these devices. The cutoff frequency fT of extrinsic current gain | h21|2 and maximum oscillation frequency fmax 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.