Comparison of vanadium dioxide films produced via sol-gel and sputtering techniques

The purpose of this work is to compare thin films of vanadium dioxide (VO2) produced via a sol-gel process and a reactive sputtering technique. The sol-gel process used was based on vanadium oxide triisopropoxide precursor. This was converted to sol in dried ethanol by adding water, and the substrates were then dip coated with a controlled draw method in an inert atmosphere. After drying this was followed by a final reduction stage in a low oxygen partial pressure atmosphere. The reactive sputtering technique used carefully controlled deposition rates from a vanadium metal target in argon/oxygen atmosphere to ensure correct stoichiometry. The films were deposited on silicon substrates and were tested optically and electrically above and below the transition temperature. Results of transmission and reflectivity (at near normal incidence) in the infrared region of the spectrum, and electrical conductivity are presented. The results show that the sol-gel technique provides a viable alternative method to sputtering for the production of thin films of vanadium dioxide.