| The metal-insulator transition (MIT) in VO2 induces a dramatic change in electric, dielectric and optical characteristics in the vicinity of room temperature. This fascinating phenomenon has attracted great attention from fundamental research to reveal its mechanisms relevant to the electronic correlation as well as from applications to exploit its effect in novel electronic and photonic devices.;This dissertation includes detailed studies on the correlation among microstructure characteristics, functional electrical and dielectric properties, and chemical composition of VO2 thin films as well as the critical effects of synthesis conditions on them and their relationships on the basis of electrical transport measurements, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction analysis.;We also demonstrated the novel post-deposition heat treatment method based on photon irradiation to modify MIT properties of VO2 thin films at temperature much lower than the synthesis temperature and showed the excellent stability of the MIT functionality of VO2 thin films through multiple cyclic transition experiments along with electric and structural property characterizations.;Using experimental combination of temperature-variable Kelvin probe microscopy, electric property characterizations, and in-depth XPS profiling, we explored the discrepancy of MIT evolution on the film surface and inside bulk region of VO2 films in terms of work function, stoichiometry, and film conductivity. Further, we have introduced novel approaches to investigate MIT phenomena in nanoscale utilizing simple exploratory capacitor and metal-oxide-semiconductor structures based on VO2 thin layers. |
