Thin Solid Films, Vol.682, 29-36, 2019
Fabrication and characterization of furnace oxidized vanadium dioxide thin films
Vanadium dioxide thin films have been prepared on lightly doped silicon substrates via the electron beam evaporation of pure vanadium and subsequent furnace oxidation in an oxygen environment at 300 degrees C. The as-fabricated thin films exhibit a phase transition at 68 degrees C, a 26% change in transmittance at a near-infrared wavelength of lambda = 2.5 mu m and a 17% change in transmittance at a mid-infrared wavelength of lambda = 10 mu m with temperature. The composition of the VO2 has been investigated using X-ray diffraction and Raman spectroscopy. The morphology and thicknesses of the thin films have been characterized using atomic force microscopy. Fourier transform infrared spectroscopy is employed to investigate the temperature-dependent optical properties of the prepared VO2 thin films. The dielectric constants of the insulating and metallic VO2 are fitted to a Lorentz model and dispersion model, respectively. Furthermore the heating and cooling curves of the prepared films are presented, showing a transition range of 57 degrees C to 77 degrees C upon heating and a transition range of 37 degrees C to 57 degrees C upon cooling. Lastly, the temperature-dependent filling fraction of the prepared films is determined and a model for the optical properties of the fabricated VO2 in phase transition is presented.