Direct current and alternating current performance in InGaP/GaAs FETs using airbridge gate with multiple piers

Abstract

This paper reports dc and ac performance in airbridge-gate doped channel field-effect transistors (DCFETs). The key features are (1) very high doping density in a V-shape-like quantum channel and (2) an airbridge gate with multiple piers. The measured peak carrier concentration and sheet carrier density are and with an electron mobility of at room temperature. Both airbridge-gate and mesa-gate DCFETs were fabricated on the same wafer. The former has its gate-feeder directly lie on multiple piers while the latter has part of the gate feeder come to rest upon the mesa ramps. In the case of dc performance investigation, we find that the gate feeder upon the mesa ramp strongly affects behaviours of the Schottky contact. Additional leakage current, induced barrier lowering, reduced breakdown voltage and temperature-dependent characteristics were observed for mesa-gate DCFETs. For a airbridge-gate (mesa-type) DCFET, the measured output current at and the maximum transconductance are , and , respectively. In case of ac performance measurement, the airbridge-gate and mesa-type FETs exhibit of 17 and 14 GHz and of 32 and 28 GHz, respectively.