Abstract
The effects of annealing times on the structural and electrical properties of ZnO thin films by XRD, FTIR, and dc conductivity were investigated. The XRD reveal the presence of hexagonal wurtzite structure of ZnO with preferred orientation (002). The grain sizes were found to be in the range 7.765-15.905 nm. The values of optical phonon frequency (v(o)) were obtained to be 1.26-1.44 x 10(13) Hz. The electrical conductivity shows that all samples are semiconductor and it decreases with increasing annealing times. The calculated activation energy for the films was found to be 0.0322-0.126 eV. The increase in electric conductivity in the films annealed at 400 degrees C for 1 h compared to that of the film annealed at 400 degrees C for 4 h can be attributed to the decrease in grain boundary scattering due to the reduction in grain size. (C) 2014 Elsevier Ltd. All rights reserved.