Cu-doped Mg0.2Zn0.8O thin films were synthesized by sol-gel spin coating. We investigated the microstructural and optical characteristics of the Cu-doped Mg0.2Zn0.8O thin films. By increasing the Cu content of the source, Cu-doped Mg0.2Zn0.8O thin films were phase-separated into Cu-rich and Cu-poor areas, which could be a result of the limited Cu solubility in theMg(0.2)Zn(0.8)O lattice. As the annealing temperature increased, the crystallinity of the Cu-doped Mg0.2Zn0.8O thin films improved. Cu doping in Mg0.2Zn0.8O thin films resulted in a decrease of both intensities for UV and visible emissions without a shift of the peak positions in the photoluminescence spectrum. (C) 2013 Elsevier B.V. All rights reserved.