AlGaInP/GaInAs/GaAs MODFET devices: candidates for optoelectronic integrated circuits

Abstract

Modulation doped field effect transistors (MODFETs) with a p + -GaAs gate structure were fabricated from AlGaInP/GaInAs/GaAs heterostructures for the first time. Self-aligned devices with a gate length of 0.7 μm exhibit drain currents of 330 mA mm −1, transconductances of 200 mS mm −1 and very small gate currents below 50 nA even at gate-source voltages of −5 V. Furthermore, large gate-drain diode breakdown voltages in excess of 30 V are observed. Short gatelength devices (0.3 μm) show a good r.f. performance with a current gain cut-off frequency of 60 GHz and a maximum frequency of oscillation of 140 GHz.