A High Performance In_0.7Ga_0.3As MOSFET with an InP Barrier Layer for Radio-Frequency Application

We demonstrate a high performance implant-free n-type In_0.7Ga_0.3As channel MOSFET with a 4-nm InP barrier layer fabricated on a semi-insulating substrate employing a 10-nm Al₂O₃ as gate dielectric. The maximum effective channel mobility is 1862 cm²/V?s extracted by the split C–V method. Devices with 0.8 μm gate length exhibit a peak extrinsic transconductance of 85 mS/mm and a drive current of more than 200 mA/mm. A short-circuit current gain cutoff frequency f_T of 24.5 GHz and a maximum oscillation frequency f_max of 54 GHz are achieved for the 0.8 μm gate-length device. The research is helpful to obtain higher performance In_0.7Ga_0.3As MOSFETs for radio-frequency applications.