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°C under nitrogen (N2) atmosphere, which exceeds the softening point of soda glass of ~500°C. In this study, we successfully reduced the baking temperature to 450°C 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°C.