Raman study of electric-field-induced first-order metal-insulator transition in VO_2-based devices

摘要

An abrupt first-order metal-insulator transition (MIT) as a current jump has been observed by applying a dc electric field to Mott insulator VO_2-based two-terminal devices. The size of the jumps was measured to be asymmetrical depending on the direction of the applied voltage due to heating effects. The structure of VO_2 is investigated by micro-Raman scattering experiments. An analysis of the Raman-active A_g modes at 195 and 222 cm~(-1), explained by pairing and tilting of V cations, and 622 cm~(-1), shows that the modes below a low compliance (restricted) current do not change when the MIT occurs, whereas a structural phase transition above the low compliance current is found to occur secondarily, due to heating effects in the device induced by the MIT. The MIT has applications in the development of high-speed and high-gain switching devices.