Atomic Resolution Study of VO2 Metal-Insulator Transition As Field-Effect Transistors

There has been long-standing interest in ultra-fast Metal-Insulator Transition (MIT) in VO₂ because of their possible applications in data processing systems specially field-effect transistors. The MIT in VO₂ is associated with a structural phase transition, sharp resistivity and optical transparency changes by several orders of magnitudes, which happens close to room temperature (at ~ 340 K). The phase transition occurs from a monoclinic (M) structure to a tetragonal rutile (R) structure. The present work investigates the effect of W dopants in MIT of individual single-crystalline VO₂ nanowires by use of aberration corrected scanning transition electron microscopy and in situ TEM. In this study different doping concentration of W were used, which corresponds to different transition temperatures around 340 K. The atomic scale Z-contrast imaging of individual single-crystalline W_xV_1-xO₂ nanowires indicates W dopant atoms and the strain caused by W atoms in in the structure. The localized strain caused by dopants play critical role in metal-insulator phase transition and control of electrical property of doped VO₂.