Preparation and characterization of vanadium pentoxide by spray pyrolysis technique

Abstract

A chemical spray pyrolysis technique was used to deposit a vanadium pentoxide (V2O5) thin films on glass substrate with a deposition temperature ranged from 300°C to 500°C in step of 50°C. From ammonium Meta vanadate aqua precursor solution molarity of (0.1 M) was used as a source of vanadium. The effect of deposition temperature on structure, morphological, electrical conductivity and optical properties was analyzed at constant deposition time, solution molarities and the distance between spray nozzle and substrate. X-ray diffraction patterns shown that an orthorhombic cubic structure with growth along (001) plane. With increasing the substrate temperature, the electrical conductivity was increased, and the scanning electron microscopy clarified that the crystalline of V2O5 thin films was effectively modified. The optical results revealed that energy band gap of V2O5 films deposited at 400oC, 450oC and 500oC is 2.38 eV for direct allowed transition. Based on the observed results the V2O5 phase can be well controlled by altering the substrate temperature. All prepared thin films up to 400oC show transparency in both visible and near IR region. The effect of deposition time (5 min to 20 min) in step of (5 min) on the electrical and optical properties of V2O5 prepared at 450oC deposition temperature was studied. The results showed that, the conductivity increased with increasing the deposition time. The highest conductivity values (9.5×10^9) Ω-1 cm-1 was obtained for the sample prepared at deposition time of 20 min. It can be seen that transmission and reflection of the film deposited for 5 min has the highest value that can be attributed to the thickness effect of the prepared samples. Keywords: V2O5, XRD, Morphological, Optical, Electrical properties, Deposition temperature, deposition time, Crystallinity and grain growth.