Two and three terminal gallium arsenide FET optical detectors

The changes in source-drain current and substrate voltage as a function of illumination intensity have been measured for two and three terminal GaAs FET structures. At low frequency, comparably high gains were observed in devices with and without gate metallization. The photo-response is probably due to a channel width modulation by a positive photovoltage developed between the high resistivity substrate and the n-epi channel.