Cu–ZnO-Ag nanocrystalline thin films with improved nonlinear optical parameters and magnetic properties for optoelectronics and spintronic applications

The current work investigated the third-order nonlinear optical parameters and magnetic properties of Cu–ZnO-Ag nanostructured films with variation of Cu doping level grown by spin coater. All the films revealed a more abundant hexagonal wurtzite structure of ZnO with a preferred growth along the (002) plane, as can be seen from X-ray diffractograms. Low-intensity and broad diffraction peak along the (002) plane suggests that the films are composed of few nanometer grains. Raman spectra confirmed a pure ZnO film growth as it showed characteristic vibration modes at 500 and 1050 cm⁻¹. The film co-doped with 1.0 wt.% (Cu, Ag) exhibits higher transmittance than other compositions, whereas the bandgap of the films reduced as the Cu doping level in the ZnO system increased. The room-temperature emission spectra of the samples depicted characteristic UV along with visible light emission. In addition, all compositions of the films exhibited a nonlinear optical nature that is influenced by the Cu doping variation. The Z-scan investigation illustrates that the samples showed remarkable improvement in the third-order nonlinear optical parameters after (Cu, Ag) co-doping in the ZnO system. On the other hand, significant improvement in ferromagnetism was observed from 10.0 emu/cc to 36 emu/cc as the Cu doping concentrations increased. The above-mentioned investigation confirmed that the Cu–ZnO-Ag alloys nanostructured thin films could be potential candidates for optoelectronics and spintronic applications.