The current-voltage characteristics of a gas discharge system in parallel-plane geometry are studied. The gas discharge system with a photosensitive semiconductor cathode have been studied in a wide range of the gas pressures p (21.3−1013 hPa), inter-electrode distances d (10μm−5mm), and conductivities of the semiconductor. Gallium arsenide $(10^7 -10^8\, \Omegarm\ {\rm cm})$ has been used as the semiconducting cathode. The cathode was irradiated on the back-side with light in a particular wavelength range that was used to control the photoconductivity of the material. The semiconductor material was found to "stabilize" the discharge. When the current is increased above the stable limit, breakdown or small current oscillations begin. The filamentation was primary due to the formation of a space charge of positive ions in the discharge gap which changed the discharge from the Townsend to the glow type.