Synthesis, structural and ellipsometric evaluation of V 2 O 5 nanowires

V₂O₅ nanowires (NWs) were grown on Si (100) and quartz substrates using evaporation–condensation method with the VLS growth technique. The chemical composition of the synthesized nanostructures was analyzed using energy dispersive analysis of X-ray (EDAX). The surface morphology and crystal structure of the synthesized NWs were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The XRD pattern revealed an orthorhombic symmetry of the deposited NWs while the SEM showed randomly distributed NWs with diameters of 50–200 nm and lengths in the range of 0.8–1.5 μm. The spectroscopic ellipsometry data for V₂O₅ NWs films were acquired in the wavelength range 400–2100 nm. The thickness and optical constants were obtained from the data fits. The estimated refractive index for V₂O₅ NWs was found to be 2.24 at λ=626.30 nm. The indirect and direct band gap values were calculated and found to be 2.26±0.02 eV and 2.83±0.02 eV, respectively. The Urbach energy E_u value was 286 meV.