Photoconductors with channels that lie in the surface depleted region of a GaAs epitaxial structure are described. These devices have microampere photocurrent at saturation conditions under 0.3 mW illumination and exhibit photoconductive gain. The dark current is in the nanoampere range and the noise equivalent power is of the order of 10-12W/√Hz. In contrast to other photoconductors, their low frequency responsivity is of the same order as that in the GHz region, alleviating problems of equalization necessary in receiver applications. As well, these devices exhibit over 60 dB isolation and sub-nanosecond switching time as optoelectronic switches.