The fabrication and visible-near-infrared optical modulation of vanadium dioxide/silicon dioxide composite photonic crystal structure

We demonstrated a visible and near-infrared light tunable photonic nanostructure, which is composed of vanadium dioxide (VO₂) thin film and silicon dioxide (SiO₂) ordered nanosphere arrays. The vanadium films were sputtered on two-dimensional (2D) SiO₂ sphere arrays. VO₂ thin films were prepared by rapid thermal annealing (RTA) method with different oxygen flow rates. The close-packed VO₂ shell formed a continuous surface, the composition of VO₂ films in the structure changed when the oxygen flow rates increased. The 2D VO₂/SiO₂ composite photonic crystal structure exhibited transmittance trough tunability and near-infrared (NIR) transmittance modulation. When the oxygen flow rate increased from 3 slpm to 4 slpm, the largest transmittance trough can be regulated from 904 to 929 nm at low temperature, the transmittance troughs also appear blue shift when the VO₂ phase changes from insulator to metal. The composite nanostructure based on VO₂ films showed visible transmittance tunability, which would provide insights into the glass color changing in smart windows. (orig.)