Nanostructured CexZn1−xO thin films: Influence of Ce doping on the structural, optical and electrical properties

Abstract

Thin films of CexZn1−xO thin films were deposited on glass substrates at 400°C by nebulizer spray pyrolysis technique. Ce doping concentration (x) was varied from 0 to 10%, in steps of 2.5%. X-ray diffraction reveals that all the films have polycrystalline nature with hexagonal crystal structure and high preferential orientation along (002) plane. Optical parameters such as; transmittance, band gap energy, refractive index (n), extinction coefficient (k), complex dielectric constants (εr, εi) and optical conductivity (σr, σi) have been determined and discussed with respect to Ce concentration. All the films exhibit transmittance above 80% in the wavelength range from 330 to 2500nm. Optical transmission measurements indicate the decrease of direct band gap energy from 3.26 to 3.12eV with the increase of Ce concentration. Photoluminescence spectra show strong near band edge emission centered ∼398nm and green emission centered ∼528nm with excitation wavelength ∼350nm. High resolution scanning electron micrographs indicate the formation of vertical nano-rod like structures on the film surface with average diameter ∼41nm. Electrical properties of the Ce doped ZnO film have been studied using ac impedance spectroscopy in the frequency range from 100Hz–1MHz at different temperatures.