Microstructure, surface morphology and optical properties of Na x Cu y Zn1−x−y O thin films

Abstract

Na x Cu y Zn1−x−y O thin films were prepared by sol–gel method on quartz glass. The effect of Na (or Cu) doping on the microstructure, surface morphology, optical properties of the thin films was investigated. The Na0.1Cu0.01Zn0.89O thin film has the largest average grain size and the best preferential c-axis orientation, which may be attributed to the difference in ionic radius between Zn and Na (or Cu). The Na0.1Cu0.01Zn0.89O thin film also presents denser morphology with little voids and the smallest optical band gap, which may be attributed to band edge bending and the larger grain size. The largest intensity of A1(LO) modes may be due to the major structural defect concentrations. The quenching of UV and visible emissions, which may be attributed to the increase of non-radiative recombination transition, has been observed in the Na0.1Cu0.01Zn0.89O and Na0.1Cu0.02Zn0.88O thin films.