The structural properties of a thin ZnO film synthesized by a reactive ion-plasma method have been studied. It is shown that a combination of reactive ion-plasma sputtering and pulsed electron beam deposition methods allows the formation of a thin-film ZnS–ZnO heterostructure with few structural defects. The results of a study of the optical and photoelectric properties of ZnS–ZnO in the wavelength range from 0.26 to 0.45 μm are presented. The spectral dependence of the frequency shift of surface acoustic waves under the influence of ultraviolet radiation on the surface of the ZnS–ZnO heterostructure of a photodetector, based on an acoustoelectronic amplifier, has been studied.