Effect of Cu-Doping Levels on the Structural and Optical Properties of SnO2 Thin Films Prepared by Chemical Spray Pyrolysis

In this research, chemical pyrolysis method was employed to synthesize nanocrystalline pure SnO 2 and copper-doped SnO 2 films (at different doping levels: 3%, 5%, and 7%) on glass substrates at 350°C. X-ray diffraction (XRD) results reveal the prepared films are polycrystalline with a tetragonal crystal structure and the intensity of peaks decreased with increased doping ratio of copper. Field Emission-Scanning Electron Microscope (FESEM) results confirm that the particle size decreases as Cu-doping increase. EDX images show the presence of Sn, Cu, and O in the structures of the prepared films. Optical results show acceptable transmittance at the middle of the visible region (80% for 7% Cu doping). Additionally, the optical energy gap of the pure SnO 2 was calculated to be 3.75 eV, and this energy gap increased to 3.90 eV with higher levels of Cu doping. The absorption coefficient decreased as the Cu doping concentration increased.