Structural and optical properties of nanostructural V_2O_5 thin films deposited by spray pyrolysis technique: Effect of the substrate temperature

摘要

V_2O_5 thin films were deposited on glass substrates by spray pyrolysis technique. The variation in the structural and optical properties with a variation in the substrate temperature was investigated by means of X-ray diffraction (XRD) and UV-vis spectrophotometer. XRD was used to reveal the possible orientations of crystallites in the films prepared at different substrate temperatures ranging from 200 ℃ to 550 ℃. The results showed that by increasing the temperature, the films grew along the (001) direction with an orthorhombic structure. The crystallite size was calculated using the Scherrer equation and observed that it increased with elevating the substrate temperature to 450 ℃, but decreased when further increasing it.The highest transmittance was achieved when films were deposited at 550 ℃. The absorption edge was estimated by using the Tauc plot. In the range 350 ℃-550 ℃, a shift of the absorption edge from 2.5 eV to 2.8 eV was observed due to the formation of chemical bonds at the V_2O_5 film-substrate interface at high substrate temperatures (>450 ℃). Field emission scanning electron microscopy showed that nanorods were formed when depositing at 500 ℃. We conclude that by altering the substrate temperature the size of crystallites can be well controlled.