Temperature-dependent Optical Characterization of VO2 Thin Film Prepared from Furnace Oxidation Method

Thermochromic vanadium dioxide (VO2 ) thin films have been deposited on quartz substrates via a two-step furnace oxidation method. First pure 2 metallic vanadium thin films are deposited on quartz substrates using electron beam evaporation. Then the vanadium films are oxidized in an atmospheric tube furnace to produce stoichiometric VO . X-ray diffraction measurements confirm the composition of the prepared films. Temperature- dependent spectral transmittance measurements within the optical range reveal a 57% change upon transition at a wavelength of λ = 2.5 μm, indicating good potential for energy applications. The heating and cooling behaviors of the VO thin films on quartz are also investigated, and the VO transitions 2 2 from an insulator to a metal at 345 K upon heating. There is approximately 20 K of hysteresis between the heating and cooling curves. The dielectric constants of the furnace oxidized VO for both the insulating and metallic phases are fitted to a dispersion model for the visible and near-infrared regime. 2 Excellent thermal stability of the fabricated VO thin film from cryogenic to high temperatures is shown with in-situ optical measurements.