Growth and phase transition characteristics of pure M-phase VO_2 epitaxial film prepared by oxide molecular beam epitaxy

摘要

VO_2 epitaxial film with large size has been prepared by oxide-molecular beam epitaxy method on Al_2O_3 (0001) substrate. The VO_2 film shows a perfect crystal orientation, uniformity, and distinct metal-insulator phase transition (MIT) characteristics. It is observed that the MIT character is closely associated with the crystal defects such as oxygen vacancies. By controlling the growth condition, the MIT temperature can be tuned through modifying the content of oxygen vacancies.The role of the oxygen vacancies on the phase transition behavior of this VO_2 film is discussed in the framework of the hybridization theory and the valence state of vanadium.