APCVD of thermochromic vanadium dioxide thin films -: solid solutions V2-xMxO2 (M = Mo, Nb) or composites VO2:SnO2

Atmospheric pressure chemical vapour deposition of V2-xMxO2 (M = Mo, Nb; X = 0.01-0.003) thin films was achieved on glass substrates from the reaction of VOCl3, H2O and MCl5. Comparable reactions with SnCl4 formed SnO2 : VO2 composites. The ease with which solid solutions or composite films formed was related to the relative reaction rates. The films were characterised by X-ray diffraction, Raman, X-ray photoelectron spectroscopy and scanning electron microscopy. Doping of the VO2 phase was shown to affect both the growth morphology and the thermochromic properties of the films. The Mo-doped VO2 films showed a thermochromic switch of 47 degrees C with a narrow hysteresis (4-6 degrees C).