Effects of Mg Additions on Microstructure and Optical Properties of Sol-Gel Derived ZnO Thin Films

Abstract

Polycrystalline thin-films of Zn_1−xMg_xO (0≤x≤0.36) have been prepared by a sol-gel method and a spin-coating technique. In this work, the authors investigate the effects of the Mg addition on crystallization, microstructure and optical properties for ZnO thin films. Mg was incorporated into ZnO thin films that were deposited onto glass substrates by a spin coating technique. The as-deposited films were preheated at 300°C for 10 min and then annealed at 500°C for 1 h. The results show that addition of Mg-species in ZnO films markedly decreased surface roughness, improved transparency in the visible range and increased resistivity. Among the Zn_1−xMg_xO films investigated in the present study, the Zn_0.8Mg_0.2O thin film exhibited the best properties, namely single wurzite phase, an optical transmittance of 94.7%, an RMS roughness of 1.63 nm and a resistivity of 8.3×10⁵ Ω-cm.