Fabrication and characterization of copper doped zinc oxide by using Co-sputtering technique

Abstract

Cu doping can change the properties of ZnO thin film. In previous studies, most papers reported on moderate doping level of Cu and used ZnO as a target with Cu chip incorporated into it. This paper reports the effects of moderate and higher Cu doping level (12%–28%) on the ZnO thin film, fabricated by using magnetron co-sputtering technique of pure ceramic ZnO and metal Cu target at room temperature. The effects of different Cu concentration on the crystal structure, surface morphology, optical properties and electrical properties were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), ultraviolet-visible (UV-VIS) spectrophotometer and Hall measurement with four-point Van der Pauw configuration respectively. XRD results indicated that ZnO thin films with hexagonal wurtzite structure was fabricated. Moderate Cu-doped ZnO has stronger preferential orientation towards c-axis compared to heavily doped and pure ZnO. In heavily Cu-doped region (24%-28%), there are secondary phases detected, Cu metallic (111). Transmittance of all films in the visible region are more than 75%. Results obtained from transmittance data are used to calculate the optical band gap of the thin film. Energy gap reduction is observed when Cu is introduced into ZnO.