Lateral scale down, of InGaAs/InAs composite-channel HEMTs with tungsten-based tiered ohmic structure for 2-S/mm gm and 500-GHz fT

A laterally scaled-down ohmic structure and an InGaAs/InAs. composite channel improve the de and RF characteristics of InP-based HEMTs. We reduced the distance between the gate and ohmic metal to less than 100 nm and to form sub-100-nm-long gate simultaneously, and also introduced device passivation for future construction of subterahertz-band integrated circuits. A 50-nm-gate HEMT exhibiting extrinsic transconductance of 2.0 S/mm and extrinsic current gain cutoff frequency (f(T)) of 496 GHz was successfully fabricated, with this technology. This is the first report of a transistor with both 500-GHz-class f(T) and large current drivability.