(Cu, Fe, Co, or Ni)-doped tin dioxide films deposited by spray pyrolysis: doping influence on film morphology

The results of structural characterization of SnO2 films doped by impurities such as Fe, Cu, Ni, and Co during spray pyrolysis deposition from 0.2 M SnCl4–water solutions are presented. The change of parameters such as film morphology, the grain size, texture, and the intensity of X-ray diffraction peaks were controlled. For structural analysis of tested films, we used X-ray Diffraction, Scanning Electron Microscopy, and Atomic Force Microscopy techniques. It was shown that the doping promoted the change of the film morphology and the decrease of the SnO2 grain size; however, these changes were not great. The doping influence becomes apparent more obviously for thin films and the films deposited at low temperatures (Tpyr * 350 C). At higher pyrolysis temperatures (Tpyr * 450 C), the influence of the doping on both the grain size and the film morphology was weakened. We concluded that used additives had dominant influence on the structural properties of SnO2 at the initial stages of the film growth, as well as at the stages of twinning and agglomeration of the SnO2 crystallites. It was shown that the increase in the contents of the fine dispersion phase in as-deposited film is an important consequence of the SnO2 doping.