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

Abstract

In this research, chemical pyrolysis method was employed to synthesize nanocrystalline pure SnO2 and copper-doped SnO2 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 SnO2 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.