Surface morphology and optical properties of Na-doped ZnO thin films

ZnO thin films with different Na doping content were prepared by sol-gel method. The effects of Na doping content on morphology and optical properties of ZnO thin films were investigated by XRD, Raman spectrometer, AFM, SEM, and UV-vis spectrophotometer, respectively. XRD and Raman spectra analysis indicate that the 8.0 at% Na-doped ZnO thin film has the optimal preferential c-axis orientation and the maximum residual tensile stress. AFM and SEM images show that mean particles diameter and roughness of the thin films increased as the Na doping content increasing. The average optical transparency of the thin films was higher than 80% in the visible range. Optical band gap of the thin films increases from 3.283 eV to 3.305 eV as the Na doping content increased from 0 to 10at%.