Optimised atmospheric pressure CVD of monoclinic VO2 thin films with picosecond phase transition

Monoclinic vanadium oxide (VO2) thin films with low roughness values were deposited and optimised by atmospheric pressure chemical vapour deposition using vanadium tetrachloride (VCl4) and water (H2O). Smooth VO2 films with good transmittance properties were successfully produced on fluorine doped tin oxide/borosilicate substrates. Systematic investigations confirmed that the quality (including phase) of films being produced strongly depended on substrate, deposition time, temperature, and precursor ratio within the process. Optical characterisation using ellipsometry revealed a strong thermochromic response of the films with a large change in the dielectric function, while time-resolved pump-probe transmission showed the picosecond nature of the phase transition.