Metal-Insulator Transition in Thin Film Vanadium Dioxide

Abstract

Recent advances in thin film growth of transition metal oxides coupled with the discovery of fascinating phenomena such as superconductivity and colossal magneto-resistance has caused an enormous interest in correlated electron effects from technological and fundamental science perspectives. Vanadium dioxide (VO2) is one of the most studied correlated electron systems that exhibits a dramatic metal–insulator transition (MIT) near room temperature. The study of this unique material offers prospects of developing a novel kind of electronics with advanced functionality and advancing fundamental science of correlated electron effects. A review of the properties of VO2 is given with special attention to the MIT. Growth conditions for synthesis of high quality VO2 are described, the crystal structure of the material is elucidated, and the relationships between electrical parameters and material morphology are defined. X-ray absorption and photoemission experiments revealed the changes in the energy band structure upon the crossing of the MIT. The analysis of near-Fermi level density of states, the correlation between the band structure and electron transport parameters, and the dispersion of the infrared reflectance of VO2 thin films help understanding the physics behind the MIT. Hall effect experiments provide the data on the carrier density and electron mobility across the MIT – important parameters in the Mott theory of MIT. VO2 devices and possible applications in electronics are discussed.