Influence of lattice distortion on phase transition properties of polycrystalline VO2 thin film

Abstract In this work, high power impulse magnetron sputtering was used to control the lattice distortion in polycrystalline VO 2 thin film. SEM images revealed that all the VO 2 thin films had crystallite sizes of below 20 nm, and similar configurations. UV–vis-near IR transmittance spectra measured at different temperatures showed that most of the as-deposited films had a typical metal–insulator transition. Four-point probe resistivity results showed that the transition temperature of the films varied from 54.5 to 32 °C. The X-ray diffraction (XRD) patterns of the as-deposited films revealed that most were polycrystalline monoclinic VO 2 . The XRD results also confirmed that the lattice distortions in the as-deposited films were different, and the transition temperature decreased with the difference between the interplanar spacing of the as-deposited thin film and standard rutile VO 2 . Furthermore, a room temperature rutile VO 2 thin film was successfully synthesized when this difference was small enough. Additionally, XRD patterns measured at varied temperatures revealed that the phase transition process of the polycrystalline VO 2 thin film was a coordinative deformation between grains with different orientations. The main structural change during the phase transition was a gradual shift in interplanar spacing with temperature.