Engineering the nonlinear optical and electrical properties of Sn-doped CuO thin films via controlled doping

This study investigates the influence of tin (Sn) doping on copper oxide (CuO) thin films at various concentrations using the spray pyrolysis technique. The structural, morphological, electrical, optical, and nonlinear optical properties were analyzed. X-ray diffraction confirmed the polycrystalline nature and monoclinic structure of CuO. Raman spectroscopy revealed the formation of secondary phases, including tin dioxide (SnO₂) and cupric peroxide (CuO₂), at 5 wt% doping. Ultraviolet–visible spectroscopy indicated a significant band gap variation at 5 wt% Sn doping compared to other concentrations. Scanning Electron Microscopy showed that Sn doping strongly influenced the surface morphology of the thin films, leading to agglomeration. Atomic Force Microscopy confirmed an increase in surface roughness with higher Sn content. Z-scan analysis indicated variations in the effective nonlinear optical absorption coefficient with increasing Sn concentration. Hall effect measurements confirmed the p-type nature of the films, and resistivity increased with Sn doping. These findings highlight the substantial impact of Sn doping on the structural, electrical, and nonlinear optical characteristics of CuO thin films.