Texture coefficient and band gap tailoring of Fe-doped SnO2 nanoparticles via thermal spray pyrolysis

An investigation of Fe-doping effect on SnO2 thin films was performed in this study using thermal spray pyrolysis (TSP) method. The surface morphology and structural, optical and electrical properties were studied by field energy scanning electron microscope (FESEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy and four-point probe method. FESEM images demonstrate that the surface morphology of the as-deposited films varies when Fe-doping content varies. XRD studies reveal that crystallite size and preferential growth orientations of the films are dependent on Fe-doping concentrations. The grain size is found to decrease with the increase in Fe content. These studies also specify that the films have tetragonal rutile-type structure with mixed secondary phases. The texture coefficient value of (110) plane increases with the concomitant in-plane (220) decrease in higher doping concentrations. The resistivity and the optical absorbance are found to increase with Fe concentration. The direct optical band gap decreases from 3.94 to 3.52 eV with increasing Fe content.