Millimeter‐wave in0.17Ga0.83as power mesfets on GaAs(100) substrates

Abstract
In0.17Ga0.83As MESFETs were grown on GaAs(100) substrates by molecular beam epitaxy (MBE). The structure comprised an undoped, In0.17Ga0.83As buffer layer grown directly on GaAs and an In0.17Ga0.83As active layer doped to 5 × 10+ 17cm−3. The defect structure was characterized by cathodoluminescence (CL) in a scanning electron microscope. FETs with 0.25‐μm gate length and 50‐μm gate width were fabricated using a standard processing technique. Excellent dc and microwave performance characteristics were obtained. The best device showed a transconductance (gm) of 400 mS / mm and a current‐gain cutoff frequency (fT) of 75 GHz. At 60 GHz, it delivered a power density of 0.50 W / mm with a gain of 4 dB and a power‐added efficiency of 20%, indicating its superior performance over a standard AIGaAs / GaAs HEMT.