Surface recombination and carrier-frequency-dependent intrinsic parameters of an ion-implanted GaAs OPFET

Surface recombination and carrier-frequency-dependent intrinsic parameters of an ion-implanted GaAs optical field effect transistor RF switch have been analysed. The study reveals that the gate-source capacitance increases with gate-source voltage, at first slowly and then sharply under enhancement mode with an increase of modulating frequency. However, surface recombination reduces these effects depending upon the trap centre density. The surface recombination effect becomes significant only when the trap centre density is nearly equal to or greater than 10(22) m-2. These variations are small in depletion devices. The drain-source resistance is found to increase with increasing modulating frequency, but it decreases with the reduction of trap centre density at a fixed flux density and drain-source voltage. It is also observed that the RC time constant increases significantly with gate length and reduces with increase of trap centre density at a fixed radiation flux density, modulating frequency and drain-source voltage.