The Effects of Growth Time on WO₃ Nanostructure Synthesized by HFCVD Method

Abstract

Tungsten oxide (WO_3−x) is a magic material and has attracted great interest due to its wide-ranging application to various fields of technology, including electrochromic device, photo catalysis, gas sensors, water splitting, photoelectric sensors, and lithium-ion batteries. In this paper, we report the controllable synthesis of tungsten oxide (WO₃) nanorods on silicon substrates by the Hot Filament Chemical Vapor Deposition (HFCVD) method. The growth mechanism of thin films is related to many parameters like time, pressure work, concentration of gases that are used, substrate temperature and etc. The most important parameter of the growth mechanism is time. The growth time is an important factor to control the size and shape of the final WO₃ structure. The effect of the growth time on structural, morphological and optical properties of the films has been investigated by X-ray diffraction (XRD), Field Emissive Scanning Electron Microscopy (FESEM) and UV–Vis spectrophotometer, respectively. The XRD spectra showed a single-crystal structure with a monoclinic structure at the shortest growth time. From FESEM images, it can be seen that by increasing the growth time the nanorods structure appears and continues to grow larger. Their diameter and length are 80 and 500 nm, respectively. The change of the morphology due to changing the growth time can be highlighted. Our results showed that the controlled growth of nanorods ranging from a thin to a larger diameter can be realized by appropriate choice at the deposition time. Finally, by increasing the deposition time to 180 s the reflection of the WO₃ was increased. The results can be used to guide a better understanding about the growth behavior of WO₃ nanorods and can contribute towards the development of the novel nanodevices.