Photoconductivity in metal-semiconductor-metal planar structures with ZnO:Ga and ZnO:Li films

Influence of UV radiation on photoelectric properties of ZnO:Ga and ZnO:Li films prepared by the electron-beam evaporation method was investigated. The photoconductivity was measured, using metal-semiconductor-metal planar structures where metallic aluminum was used as ohmic electrodes. The kinetics of rise and decay of the photoconductivity in these structures was studied. The change of photoconductivity under the action of UV radiation is considered as a result of the photoexcitation-relaxation into the conduction band and photochemical processes of absorption-desorption of oxygen at the film surface. The influence of a MgF2 protective layer deposited on ZnO:Ga and ZnO:Li films was studied. Measurements of the spatial distribution of the potential between the anode and cathode for determination of the homogeneity of conductivity in the investigated planar structures were performed by the moving probe method.