Non-steady-state photoelectromotive force in semiconductor crystals with high light absorption

Abstract

The influence of a high light absorption on the photoelectromotive force excited by moving interference fringes in photoconductive crystals is considered. It is shown that due to a deep penetration of the electric field pattern into the sample volume, the absolute magnitude of the output signal and its dependence on the spatial frequency of the grating may practically be the same as for low absorption. This conclusion is confirmed experimentally for semi-insulating GaAs:Cr for λ=633, 840–900, and 1064 nm. This means, in particular, that films or thin specimens of photoconductive materials can be used for fabrication of adaptive detectors of phase-modulated optical signals with the same efficiency as bulk specimens.