Thin films which were evaporated from materials with mixed ZnO:Bi ceramics and ZnSe sintered powders on ITO glass substrates at 250∼450°C, exhibit good nonlinear current-voltage characteristics. This nonlinearity is considered to result from the reduction and oxidation of ZnSe during the evaporation process, and a randomly mixed system composed of mainly ZnO and residuals of Se and ZnSe is formed.