Effect of the oxygen partial pressure on the microstructure and optical properties of ZnO:Cu films

► In this paper, ZnO:Cu thin films with c-axis preferred orientation were prepared on Si substrates by radio frequency magnetron sputtering technique. ► XRD and AFM measurements indicated that the grain orientation of the films was promoted by appropriate oxygen partial pressures. ► And with increasing oxygen ratio, the compressive stress of the films increased first and then decreased. ► A violet peak, two blue peaks and a green peak were observed from the PL spectra of the four samples. The origin of these emissions was discussed.