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

Highlights: • Thin films of Ce doped ZnO were prepared by nebulizer spray pyrolysis technique. • Films were deposited at different cerium concentrations 2.5%, 5.0%, 7.5% and 10%. • Ce doped ZnO films are found to have more grains along [0 0 2] direction. • The band gap energy was found to be decreased with the increase of Ce doping. • CexZn1−xO films ensure their stability and suitability for gas sensors. -- 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 (0 0 2) 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 2500 nm. Optical transmission measurements indicate the decrease of direct band gap energy from 3.26 to 3.12 eV with the increase of Ce concentration. Photoluminescence spectra show strong near band edge emission centered ∼398 nm and green emission centered ∼528 nm with excitation wavelength ∼350 nm. High resolution scanning electron micrographs indicate the formation of vertical nano-rod like structures on the film surface with average diameter ∼41 nm. Electrical properties of the Ce doped ZnO film have been studied using ac impedance spectroscopy in the frequency range from 100 Hz–1 MHz at different temperatures