The influence of post annealing on the structure and optical properties of vanadium oxide thin films

Vanadium and vanadium oxide films were deposited onto glass and silicon substrates at room temperature by DC magnetron sputtering and reactive DC magnetron sputtering, respectively. The effect of post annealing in air atmosphere were explored. The as-deposited vanadium and vanadium oxide films were annealed under air atmosphere at different temperatures (100-500°C) and annealing times (6, 12 hours). The structural properties of the films were studied by X-ray diffraction and scanning electron microscopy. The optical properties of the films were studied by UV-Vis spectrophotometer. The results showed that the annealed vanadium films have a formation of polycrystalline V2O5 structure while the optical transmittance is low due to the imperfect thermal oxidation. For the annealed vanadium oxide films, the vanadium oxide with the phase of V2O5 is also presented while the transmittance decreased when the annealing temperature is increased. This is due to the light loss by the scattering at the rough surface. A comparison of the results with the annealed vanadium and annealed vanadium oxide films will be discussed. Moreover, the effect of the post annealing temperature and the annealing time on the structural and optical properties will also be discussed.