Electric Field-triggered Metal-insulator Transition In Vanadium Dioxide Thin Film

As one of 3d transition metal oxides, vanadium dioxide undergoes first-order metal-insulator near 68°C. The phase transition is always accompanied by dramatic changes in optical and electrical properties. It is critical to understand the mechanism of MIT, which is still controversial between the structural phase transition and Mott transition. However, the mechanism of Mott phase transition provides an exciting opportunity to create two and multi-terminal devices where various tunable parameters such as temperature or electric field can be used to trigger the phase transition.The process about how to fabricate vanadium dioxide thin film is described in the paper. Vanadium dioxide thin films are deposited on the silicon substrate by magnetron sputtering. Then the crystal structure and composition of vanadium dioxide thin films are characterized by means of XRD and Raman scattering spectra.The paper describes the structure of micro-Raman test device. Then, the images of the test channel apply with different electric field are recorded by optical microscope. The images show that some areas of the test channel become darker in color.Some points in and out of darken area are picked to test micro-Raman. The result of micro-Raman test show that vanadium dioxide undergoes a phase transition just in darken area.A study about vanadium dioxide thin films MOS capacitance is described. The device is fabricated by semiconductor process. Then, the capacitance-voltage curves was measured under diffierent Applied voltage. And the result of MOS capacitance test show that induced charge injection can also induce phase transition of vanadium dioxide .