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Metamorphic AlInAs/GaInAs high-electron-mobility transistors (HEMTs) of 150-nm gate length with very good device performance have been grown by metal-organic chemical vapor deposition, with the introduction of an effective multistage buffering scheme. By using a combined optical and e-beam photolithography technology, submicrometer mHEMT devices have been achieved. The devices exhibit good dc and RF performance. The maximum transconductance was 1074 mS/mm. The nonalloyed ohmic contact resistance Rc was as low as 0.02 Ω·mm. The unity current gain cutoff frequency (fT) and the maximum oscillation frequency (fmax) were 279 and 231 GHz, respectively. This device has the highest fT yet reported for 150-nm gate-length HEMTs. Also, an input capacitance to gate-drain feedback capacitance ratio Cgs/Cgd of 3.2 is obtained in the device.