Growth processes of vacuum-evaporated ZnS thin films on GaAs(1 0 0) surfaces with or without electron irradiation were investigated by reflection high-energy electron diffraction (RHEED), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The electron irradiation was made with medium-energy electrons lower than 500 eV, for very short time from the slanting direction to the substrate surface. Results showed that without electron irradiation two types of orientation of the ZnS films were observed at the substrate temperature of 200-300 degreesC, depending on the chemical binding at the interface between the film and the substrate. Perfect epitaxial cubic-ZnS films were successfully obtained by using a technique of irradiation with a medium-energy electron beam (similar to10(13) electrons/(cm(2) s) at 400 eV) on the substrate at 275 degreesC. The film was flattened in a submicroscopic scale by the electron irradiation. These results are discussed in terms of the surface modifications by the interaction of electrons with the substrate surfaces. (C) 2003 Elsevier Science B.V. All rights reserved.