<title>Thermochromic nondoped and W-doped VO<formula><inf><roman>2</roman></inf></formula> films heteroepitaxially grown on glass substrate using ZnO polycrystalline films as buffer layers</title>

Abstract

Vanadium dioxide (VO2) is one of the most attractive thermochromic materials, which shows large changes in optical and electrical properties at transition temperature (Tt) close to room temperature. This thermochromic behavior has been explained by the Mott-Hubbard transition from a high-temperature rutile structure (metal phase) to a low-temperature monoclinic structure (semiconductor phase). Non-doped VO2 are characterized by Tt of 68 degree(s)C, which is rather high for general window applications. However Tt have been reported to be decreased by W or Mo dopings in which W was the most effective dopant for reducing Tt. We already reported that rf magnetron sputtering using V2O3 or V2O5 targets enable us to deposit polycrystalline thermochromic VO2 films with high reproducibility by introduction of oxygen gas (O2/(Ar+O2)equals1 to approximately 1.5%) or hydrogen gas (H2/(Ar+H2equals2.5 to approximately 10%), respectively, as reactive gases. In this study, ZnO polycrystalline films were deposited as a buffer layer between the VO2 film and glass substrate also by rf magnetron sputtering (VO2/ZnO/glass), where the ZnO films deposited on a glass substrate had been known to exhibit <001$GTR preferred orientation in the wide range of the deposition conditions.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.