Structural and optical properties of ZnO thin films prepared by sol–gel method

Abstract

In this Letter thin films of zinc oxide (ZnO) are prepared by sol–gel method and deposited on glass substrate to evaluate structural and optical properties of the film. The films were grown at different thicknesses in the range of 100–180 nm. The properties of layers were characterised using X-ray diffractometer (XRD), atomic force microscope (AFM) and optical spectrophotometer to evaluate the quality of the thin film for photovoltaic applications. The results from XRD pattern revealed that the grown films exhibit wurtzite structure with (002) preferential plane. The results from AFM data revealed that the films had nano-sized grains with a grain size from∼25 to 60 nm depending on the film thickness. The optical spectrophotometer studies exhibited direct allowed transition with an energy bandgap of 3.12–3.02 eV for films with thicknesses of 100–180 nm, respectively. The refractive index as well as extinction coefficient of films was also measured.