Controls of surface morphology on sol-gel derived ZnO films under isothermal treatment conditions

Abstract

Zinc oxide (ZnO) thin films were deposited using a spin-coating method, and the effects of the drying pressure and film thickness under isothermal conditions were investigated. A decrease in pressure and increase in thickness caused significant changes in the surface morphology of the ZnO films from a smooth surface, through a wrinkle structure, to a maze structural surface. From these results, the pattern formation is closely related to the relationship between the bending force and leveling force, which depends strongly on the fluidity of the sol during the drying process. In this case, monoethanolamine (MEA) with a low vapor pressure mainly affects the fluidity of the sol, and the evaporation of MEA can be controlled easily by changing the drying parameters. The technique developed in this study can be applied easily to build various surface patterns of ZnO films.