Comprehensive studies of interfacial strain and oxygen vacancy on metal–insulator transition of VO2 film

Abstract

As a typical strong correlation material, vanadium dioxide (VO2) has attracted wide interest due to its particular metal–insulator transition (MIT) property. However, the relatively high critical temperature (Tc) of ~68 °C seriously hinders its practical applications. Thus modulating the phase transition process and decreasing the Tc close to room temperature have been hot topics for VO2 study. In the current work, we conducted a multi-approach strategy to control the phase transition of VO2 films, including the interfacial tensile/compressive strain and oxygen vacancies. A synchrotron radiation reciprocal space mapping technique was used to directly record the interfacial strain evolution and variations of lattice parameters. The effects of interfacial strain and oxygen vacancies in the MIT process were systematically investigated based on band structure and d-orbital electron occupation. It was suggested that the MIT behavior can be modulated through the combined effects of the interfacial strain and oxygen vacancies, achieving the distinct phase transition close to room temperature. The current findings not only provide better understanding for strain engineering and oxygen vacancies controlling phase transition behavior, but also supply a combined way to control the phase transition of VO2 film, which is essential for VO2 film based device applications in the future.