OPTICAL GAIN IN PHOTOCONDUCTORS MADE OF COMPENSATED AND PARTIALLY COMPENSATED GAAS

The dc gain behaviour of GaAs photoconductors realized utilizing a par tially compensated buffer layer of an epitaxial MESFET structure as we ll as a Cr-doped semiinsulating substrate is studied. The light-power dependence of the gain hints to the dominant role of the bimolecular r ecombination process and trap-mediated gain, and only a minor role of the surface photovoltaic effect. The possible correlation between dark current and gain mechanism in the MESFET-like device is pointed out.