Fabrication of 45 nm high In component metamorphic In 0.7 Ga 0.3 As/In 0.6 Ga 0.4 As composite‐channel high electron‐mobility transistors on GaAs substrates

A 45 nm high In component metamorphic In0.7Ga0.3As/In0.6Ga0.4As composite-channel high electron-mobility transistor (mHEMT) on GaAs substrate with good DC and RF performance has been developed. The structure was grown by molecular beam epitaxy and exhibits a superior electron mobility of 10200 cm2/(V.s) and a sheet density of 3.5 × 1012 cm−2 at a room temperature. A combined optical and e-beam lithography technology was used to achieve the nanometre mHEMT device. The mHEMT device shows an extrinsic transconductance of up to 990 mS/mm and a maximum current density of 910 mA/mm. The unity current gain cutoff frequency fT and the maximum oscillation frequency f max are 187.94 and 258.62 GHz, respectively. These performances make the device well suited for millimetre-wave applications.