Nanostructured of In doped ZnO thin films were prepared on quartz substrates by the sol-gel method. The thin films were crystallized at 400 degrees C, 500 degrees C and 600 degrees C for 1 h in air atmosphere. The analyzed results were compared to investigate the structural characteristics and optical properties. The surface morphology of In doped ZnO films were different from that of the undoped ZnO films, and showed thin overlay structure. In addition, the crystallization of In doped ZnO film was depleted higher crystallized temperatures. From XRD analysis, all films exhibited hexagonal structures. Both of In(2)O(3) phases and the crystallization mechanism not only improved the peeling of structure, but also improved the morphology of In doped ZnO thin films. The chemical bonding was studied by FTIR spectra. For the photoluminescence (PL) spectrum, the optical property of the In doped ZnO film was raised at a higher crystallization concentration. Although the In(2)O(3) phases reduced the structural defects of In doped ZnO thin film, the optical effect of the residual Inu(3+) was not enhanced completely at higher crystallized temperatures. (C) 2010 Elsevier B. V. All rights reserved.