Effects of postdeposition annealing on the metal-insulator transition of VO_2-x thin films prepared by RF magnetron sputtering

We report the fabrication of textured VO_2-x films on c-cut sapphire substrates by postdeposition annealing of V₂O₃ films prepared by RF magnetron sputtering using V₂O₃ as the target. Although the prepared VO_2-x films are expected to be oxygen-deficient, overoxidation on the film surface was revealed by X-ray photoelectron spectroscopy. The metal-insulator transition (MIT) characteristics of the VO_2-x films were investigated. MIT parameters including the transition temperature, transition sharpness, and hysteresis width of the VO_2-x films were manipulated by varying the oxygen pressure during postdeposition annealing. The suppression of optical transmittance in the near-infrared region was observed by increasing the temperature through the MIT.