Effect of Na doping on the microstructures and optical properties of ZnO nanorods

Abstract

Undoped ZnO and Na doped ZnO (ZnO:Na) nanorod films have been deposited by sol–gel method using spin coating technique. The effect of Na incorporation on structural, morphological and optical properties of ZnO nanorod films was investigated. The nanorods were confirmed by the scanning electron microscopy (SEM) measurements. X-ray diffraction (XRD) measurement showed that the undoped ZnO nanorod film was crystallized in the hexagonal wurtzite phase and presented a preferential orientation along the c-axis. Only one peak, corresponding to the (002) phase, appeared on the diffractograms. Na incorporation leads to substantial changes in the structural characteristics of ZnO nanorod films. The chemical composition of the Na doped nanorod ZnO films was confirmed by X-ray photoelectron spectroscopy (XPS). Optical properties of the films were investigated with a double beam spectrophotometer with an integrating sphere. The absorption edge shifted to the lower energy depending on the Na content. The optical constants of these films, such as refractive index, extinction coefficient, optical dielectric constants and optical conductivity were determined using transmittance and reflectance spectra. The refractive index dispersion curve of the films obeys the single oscillator model. Optical dispersion parameters Eo and Ed developed by Wemple–DiDomenico were calculated.