The main characteristics of smart window was a selective blocking of infrared light. Vanadium dioxide has a phase transformation characterisitics between insulated state with transparent property and metallic state with reflective property to infrared light at specific temperature. So, vanadium dioxide was the best choice for a smart window.
The vanadium oxide thin film was deposited by RF sputtering system. The V2O5 target and several oxide target (TiO, Cr2O3, WO3, Fe2O3, NiO, CuO, Al2O3) was selected.
The crystal structure of vanadium oxide was determined by the deposition parameter or additional cation effect. Valence of vanadium ion was proportional to working pressure. The role of additional cation was the formation of compound (Ti, Cu), doping (Cr, Fe, Al), and amorphization (W, Ni). The effect of cation addition was reduction (Ti, Cr, Fe, Al) and oxidation (Cu) of vanadium ion.
The effect of metal oxide co-sputtering was 'compound formation', 'amorphization', 'control of oxygen state in chamber', and 'improvement of deposition rate'.
