EFFECTS OF SPRAY PYROLYSIS DEPOSITION PARAMETERS ON MORPHOLOGICAL, OPTICAL AND STRUCTURAL PROPERTIES OF WO3 NANOSTRUCTURED THIN FILMS

In this experimental research, tungsten trioxide (WO3) thin films were deposited using ammonium tungstate ((NH4)(2)WO4) by a simple and cost-effective technique of spray pyrolysis on top of glass substrates. The surface morphology, structural and optical properties of prepared samples were studied using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) pattern analysis and UV-Vis spectroscopy techniques, respectively. Studied deposition parameters were: substrate temperature (300, 350, 400, 450 and 500 degrees C), concentration of the precursor solution (0.01, 0.02, 0.04, 0.08, 0.1 and 0.2 M), volume of the precursor solution (50, 100, 150 and 200 mL) and the effect of pulsed spraying at different concentrations (0.01, 0.1 and 0.2 M). FESEM images showed that the surface morphology has formed like nested micro-fibrous rings with a uniform distribution all over the surface. The XRD patterns revealed that increasing the solution concentration to 0.2 M shows some peaks which can be attributed to WO3 with the hexagonal crystal structure. Transmission spectra of the samples indicate that all of the prepared samples are transparent in the visible range, with the calculated direct bandgap ranging from about 2.93 eV to 3.96 eV, depending on the deposition conditions.