GaAs field effect transistors prepared on lattice-mismatched InP substrates for monolithic optoelectronic integration.

We demonstrate for the first time a depletion mode field effect transistor fabricated on GaAs which is grown on top of a lattice- mismatched InP substrate by molecular beam epitaxy. This structure looks promising for the monolithic integration of metal-semiconductor field effect transistors (MESFET's) with photoconductive detectors and other optoelectronic devices. We observe an orientation-dependent surface conductance property. Preliminary experiments reveal a transconductance of about 20mS/mm.