Low-Temperature Deposition of VO₂ Thin Films on Glass Substrates by MOD Method

Abstract

The metal-organic decomposition (MOD) method is a promising method for the deposition of VO₂ thin films, which are expected to be used as material for smart window. However, a serious problem for such applications is that the minimum baking temperature in the previous study is 580℃ under nitrogen (N₂) atmosphere, which exceeds the softening point of soda glass of ~500℃. In this study, we successfully reduced the baking temperature to 450℃ for forming polycrystalline VO₂ thin films on glass substrates in N₂ atmosphere added with 4% H₂. When the transmittance of VO₂ thin films between the visible and near-infrared regions around the phase transition temperature was measured with a spectrophotometer, maximum values of the average transmittance at 90℃ between 400 and 800 nm was 54.4% and the maximum dimming rate for transmittance change at 1600 nm was 36.8%. Furthermore, the substitutional doping of Nb ions effectively lowered the phase transition temperature from 68℃ to 49℃ at the baking temperature of 450℃.