The DC and microwave properties of strained In0.65Ga0.35As/In0.52Al0.48As HEMTs (high-electron-mobility transistors) with double-heterojunction design are presented. The high sheet carrier density and good carrier confinement give rise to excellent device performance with very low output conductance. For 1 × 150-μm2 long-gate HEMTs, the measured cutoff frequency fT and maximum frequency of oscillation fmax are as high as 37 and 66 GHz, respectively.
