Structural and optical properties of In-doped ZnO thin films under wet annealing

Indium-doped zinc oxide (In-doped ZnO) thin films were deposited on silicon substrates by radio frequency magnetron co-sputtering of ZnO and In targets. The effects of wet annealing at various temperatures on the films were investigated. All the films had a hexagonal wurtzite structure with preferred c-axis orientations. The crystal structure of the films was improved as the wet annealing temperature was increased to 800 degrees C and then deteriorated at 900 degrees C due to the presence of cracks and porosity. The surface morphologies of the films changed significantly as the wet annealing temperature reached above 800 degrees C. Besides that, strong emission at near-band-edge of ZnO and green emission were observed as the annealing temperature increased. Overall, In-doped ZnO thin film annealed at 800 degrees C has the best structural and optical properties. (C) 2013 Elsevier B.V. All rights reserved.