WO3:Mo and WO3:Ti thin films deposited by spray pyrolysis: The influence of metallic concentration on physical properties: An electron microscopy and atomic force study

WO3:Mo and WO3:Ti thin films have been deposited on glass substrates coated with FTO(Fluorine Tin Oxide) kept at Ts= 450°C by the pulsed spray pyrolysis technique. The influence of Molybdenum (Mo) and Titanium (Ti) doping on the structural, electrical, and optical behavior of WO3thin films, has been studied by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High Resolution Electron Microscopy (HRTEM), Atomic Force Microscopy (AFM),Ultraviolet and visible (UV-Vis) spectroscopy and Surface Conductivity Methods (Four Points). Doped WO3films present similar polycrystalline structures but noticeable modifications in surface configurations at micrometric and nanometric levels, they were detected when the Mo and Ti concentration in the corresponding starting solution is increased. Variation in grain shapes, size and distribution are observed in SEM and AFM micrographs with increasing Mo and Ti doping respectively. From structural studies, a low density of crystallographic defects was detected in all the samples. It was found that variations in films surface characteristics are mainly related to each type of metallic doping and to their corresponding concentrations. Higher electrical resistivity was found in samples Mo and Ti doped with 8 and 10 at.% respectively. The greater shift in band gap values (3.50 to 3.72 eV) was detected in doped samples with Mo and Ti with 10 % atomic concentration. © 2019 Trans Tech Publications, Switzerland.