The physical processes determining the functioning of a dc discharge generated by parallel plate electrodes and especially the discharge stabilization by the GaAs semiconducting photodetector in a photographic system are studied. The photodetector was irradiated on the back-side with infra-red radiation in a particular wavelength range that was used to control the photoconductivity of the detector. The semiconductor photodetector was found to stabilize the radiation of the discharge. The current-voltage and radiation-voltage characteristics of the gas discharge cell with a semiconducting photodetector are obtained experimentally. An investigation of the effect of the voltage amplitude on the dynamics of transient processes in the plane photodetector-discharge gap structure was made for explanation of the light intensity and current decoy.