High-quality undoped ZnSe films on n-type (1 0 0)-silicon substrate were obtained by atomic layer epitaxy (ALE), in which dimethylzinc (DMZn) and hydrogen selenide (H2Se) were used as the reactants. Key growth steps are described. Growth parameters were varied to obtain films of higher quality. It was found that ZnSe monolayer growth rate is independent of substrate temperature (150-225 degrees C) and the mole fractions of both DMZn and H2Se. ZnSe epilayer characteristics were investigated by XRD, PL and electrical measurement. A single intense diffraction line was observed at 65.8 degrees, which is slightly smaller than the standard value of bulk ZnSe crystal, confirming that the epitaxial layer is a (1 0 0)-oriented single-crystalline layer. PL spectra, obtained at 7 and 300 K, showed a strong and dominant peak emission at near-band-edge emission of 2.81 eV (4412 Angstrom). Schottky diodes were fabricated from the undoped ZnSe layer and the electrical properties were measured at room temperature. From the current-voltage (I-V) characteristics, a high reverse breakdown voltage (>40 V) and an extremely low cut-in voltage of 0.6-0.8 V were obtained. On the basis of the observed ZnSe/Si epitaxial film properties, the material is suitable for fabrication of ZnSe-based blue-light-emitting diodes (LEDs) and for application in direct-current thin-film electroluminescence (DCTFEL).