Role of joule heating effect and bulk-surface phases in voltage-driven metal-insulator transition in VO2 crystal

We report the characteristics of a voltage-induced metal-insulator transition (MIT) in macro-sized VO2 crystals. The square of MIT onset voltage (V-2(CMIT)) value shows a linear dependence with the ambient temperature, suggesting that the Joule heating effect is the likely cause to the voltage-induced MIT. The combination of optical microscope images and Laue microdiffraction patterns show the simultaneous presence of a metallic phase in the bulk of the crystal with partially insulating surface layers even after the MIT occurs. A large asymmetry in the heating power just before and after the MIT reflects the sudden exchange of Joule heat to its environment. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.