GaAs MESFET Photoresponse to CW Laser Probe

An effect, in planar GaAs MESFETs, whereby a sharp increaSe in optical gain at the transistor edges occurs, is reported. This gain effect only manifests when a large resistor is inserted in ser-ies with the gate, to produce the conditions for photovoltaic gate biasing. The mechanism for increased gãin, at t'he edges, is suggested to be due to carrier photogeneration in the substrate that is subsequentlylollecteA fy tfre gate. Application in the area oI X-Y addressable transistor array imag".i, roiion detectois, opiical neural nets, GaAs X-ray detectors etc' is possible, for increased photosensitivity'