Direct current and alternating current performance in InGaP/InxGa1-xAs FETs using airbridge gate with multiple piers

This paper reports de and ac performance in airbridge-gate InGaP/InxGat-xAs 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 1.0 x 10(19) cm(-3) and 7.2 x 10(12) cm(-2) with an electron mobility of 3660 cm(2) V-1 s(-1) at room temperature. Both airbridge-gate and mesa-gate DCFETs were fabricated on the same wafer. The farmer 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 de 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. Fora 1 x 100 mu m(2) airbridge-gate (mesa-type) DCFET, the measured output current at V-GS = 0.0 V and the maximum transconductance are 660 (520) mA mm(-1), and 260 (220) mS mm(-1), respectively. In case of ac performance measurement, the airbridge-gate and mesa-type FETs exhibit f(t) of 17 and 14 GHz and f(max) of 32 and 28 GHz, respectively.