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A fabrication technique for sub-50-nm T-shaped-gate InGaAs/InAlAs high electron mobility transistors (HEMTs) lattice-matched to InP substrates and their device characteristics are presented. A 35-nm T-shaped-gate HEMT is successfully fabricated by optimizing conditions of electron beam (EB) lithography and reactive ion etching (RIE) to make an ultra-fine resist pattern and precisely replicate it on a SiO2 film, which defines gate length (Lg). The device exhibits an excellent current-gain cutoff frequency (fT) as high as 317 GHz with high controllability. This technique is considered to be very effective for device and MMIC applications in the V band and even higher frequency ranges.