In situ Raman-scattering mapping and resistance study of the VO2 metal-insulator phase transition

In this study, a large-area single-phase VO2 film was successfully prepared on a Si (100) substrate by reactive magnetron sputtering deposition. The thickness of the VO2 film is approximately 220 nm. The phase transition temperature is about 67 ?, with more than three orders of magnitude of the resistance change. X-ray diffraction patterns obtained at different temperatures indicate the coexistence of two phases during the VO2 phase transition process, where a portion of the grains first transform from a monoclinic structure to a rutile structure, and then phase transition expands throughout the film. In situ Raman-scattering mapping scans further prove that the monoclinic-to-rutile phase transition occurs gradually in polycrystalline VO2 films, in which monoclinic and rutile phases coexist from 55 ? to 80 ?. Electrical resistance of the film will change dramatically when the volume fraction of monoclinic phase decreases to 43.5%, or the volume fraction of rutile phase increases to 55.5%. The phase transition temperature differs among the grains in the polycrystalline VO2 film. This study provides an important scientific approach for elucidating the mechanism of the metal-insulator phase transition.

Automated summary

In this study, a large-area single-phase VO2 film was prepared and the coexistence of two phases during the phase transition process was observed. The gradual monoclinic-to-rutile phase transition was confirmed by in situ Raman-scattering mapping scans. This research provides important insights into the mechanism of metal-insulator phase transitions.