Structural and spectroscopic view of insulator-metal transition characteristics in epitaxial VO₂ films

Vanadium dioxide (VO₂) is interesting materials not only for the fundamental aspect owing to the unclear physical origin of the insulator-metal transition (IMT) but also for the numerous device applications such as, Mott field effect transistors, infrared detectors, tunable optical switching. Recently, many studies performed to modify the transition temperatures by doping, varying crystal orientations and strain state. Among them, the strain state is a very effective way to control the IMT characteristics. However, the presence of multivalent vanadium states, which is always in the VO₂, causes the difficulty to control the properties. In this presentation we will demonstrate how the various parameters can tune the IMT characteristic. Using spectroscopic and structural analysis we were able to correlate the variation of multivalent state and strain with IMT characteristics.