Properties of vanadium oxide film prepared using pulsed magnetron sputtering

Vanadium dioxide is a well-known thermochromic material with a metal-to-insulator transition, which is associated with a reversible transformation between monoclinic structure and tetragonal structure at a critical temperature of about 341 K. The objective of this research was to investigate the relationship between microstructure of vanadium oxide synthesized using magnetron sputtering and the thermochromic characteristics. In this study, vanadium oxide thin films were prepared on glass substrates using reactive pulsed magnetron sputtering of Ar/O₂ mixture gases at a total gas pressure of 0.8 Pa and an average power of 60 W in the partial pressure range of oxygen gas from 2% to 5%. The film thickness was about 100 nm. The film structure was analyzed using the Raman spectroscopy and X-ray diffraction (XRD) measurement. The film structure and the infrared transmittance at wavelength longer than 800 nm strongly depend on the partial pressure of oxygen gas as well as the peak target current. The peaks due to V₂O₅ or VO₂ components were observed in the measured Raman spectra, showing the narrow process window for the synthesis of VO₂-based films.