振荡(细胞信号)
电容器
电阻器
材料科学
凝聚态物理
电容感应
金属-绝缘体过渡
相变
绝缘体(电)
电压
电介质
光电子学
物理
金属
电气工程
化学
生物化学
量子力学
冶金
工程类
作者
Hyun-Tak Kim,Bong-Jun Kim,Sungyoul Choi,Byung Gyu Chae,Yong Wook Lee,Tom Driscoll,M. M. Qazilbash,D. N. Basov
摘要
We systematically investigate the characteristics of an electrical oscillation observed in two-terminal vanadium dioxide (VO2) devices. These oscillations are observed at room temperature in a simple electrical circuit without inductive components. The circuit is composed only of a dc voltage source, the VO2 device, and a standard resistor connected in series with the device. We explain why the observed oscillations are a result of the percolative metal-to-insulator transition (MIT) of VO2 and the coexistence of the metal and insulating phases. Specifically, oscillations are attributed to the construction and destruction of capacitive regions composed of regions of the semiconducting phase, (as dielectric material) and metallic phase electron carriers, induced by the MIT (as capacitor electrodes). Since the coexistence of these phases—and thus the capacitive regions—is destroyed by elevated temperature, the MIT oscillation is not explained in terms of significant heat input but rather in terms of a voltage-triggered effect. It is also discussed whether the current jump at the onset of the oscillations is driven by Mott physics or by Peierls physics relying on a structural phase transition. Furthermore, the electrical parameter space surrounding these oscillations is explored, and a generation window is identified. Within this generation window, the oscillation frequency can be continuously tuned by adjusting applied voltage or by an external circuit component, such as resistor or added capacitor. The frequency of oscillations can be increased up to >1 MHz.
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