The alloying effects on the structural and optical properties of nanocrystalline copper zinc oxide thin films fabricated by spin coating and annealing method

The present paper reports on a systematic study of the influence of Zn alloying on the structural and optical characteristics of CuZnO thin films. Nanocrystalline CuZnO thin films were prepared on p-type Si (1 0 0) substrates by spin coating from a CuO solution mixed with Zn of 0–8.0 at.%. All the prepared samples were annealed in oxygen gas atmosphere at 673 K for 2 h. A detailed characterization of the films doped with zinc was performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, photoluminescence (PL) spectroscopy, atomic absorption spectroscopy (AAS), and energy dispersive X-ray spectroscopy (EDS). The structural analyses suggest that Zn successfully occupied the Cu sites and did not change the monoclinic structure of CuO. After 4.0 at.% Zn was doped, the crystalline quality and (0 0 2) preferential orientation of the thin film improved. However, when the Zn doping concentration was above 4.0 at.%, the crystalline quality and preferential orientation of the thin film weakened in turn. The XRD and FT-IR results showed single phase CuZnO for the lower (at.% ≤ 6.0) Zn concentration, while a secondary phase of ZnO evolved for 8.0 at.%. The optical band gap, determined from the absorbance spectra, showed a blue shift with increasing Zn content. The works showed that the structural and optical properties of CuO films doped with Zn can be improved and the 4.0 at.% Zn-doped CuO thin films have the best crystallization quality and the strongest emission ability.