Ultrasonically sprayed ZnO:Co thin films: Growth and characterization

► The effect of Co doping on the physical properties of the ZnO films was reported. ► The XRD results indicated that all the films were polycrystalline. ► The optical results confirm the Co2+ ion substitution for Zn2+ ion in ZnO lattice. ► The Co doping decreased the electrical conductivity of the undoped ZnO films. ► AFM measurements were performed to obtain the surface roughness for the films.