Laterally scaled down tiered-edge ohmic structure of InP-based HEMTs for 2-S/mmg/sub m/ and 500-GHz f/sub T/

DC and RF characteristics of InP-based HEMTs were improved by employing a laterally scaled down ohmic structure and an InGaAs/InAs composite channel. Through the combination of our process technology for fabricating this structure and that for scaling down a gate length, we successfully fabricated a 50-nm-gate HEMT exhibiting extrinsic transconductance of 2.0 S/mm and extrinsic current gain cutoff frequency (f
_T
) of 496 GHz simultaneously. This is the first report of a transistor exhibiting 500-GHz f
_T
with large current-drivability