State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, People's Republic of China.
Chaos. 2009 Sep;19(3):033136. doi: 10.1063/1.3227644.
We study self-sustained terahertz current oscillation and chaotic dynamics in semiconducting single-walled zigzag carbon nanotubes using the time-dependent drift diffusion equations. The current oscillation under a dc voltage bias originates from the negative differential velocity of carbon nanotube which induces the motion and recycling of unstable domain. Numerical simulation indicates that different nonlinear oscillatory modes appear when an external high-frequency ac voltage is superimposed to the dc voltage bias and its driving amplitude varies. The appearance of different nonlinear oscillating modes, including periodic and chaotic, is attributed to the competition between the natural oscillation and the external driving oscillation. The transitions between periodic and chaotic states are carefully studied using chaos-detecting methods, such as bifurcation diagram, phase portraits, first return map, and Fourier spectrum. The resulting bifurcation diagram displays an interesting and complex transition picture with the driving amplitudes as the control parameter.
我们使用含时漂移扩散方程研究了半导体单壁锯齿型碳纳米管中自维持太赫兹电流振荡和混沌动力学。直流电压偏置下的电流振荡源于碳纳米管的负微分速度，这导致了不稳定区域的运动和循环。数值模拟表明，当外加高频交流电压叠加到直流电压偏置上且其驱动幅度变化时，会出现不同的非线性振荡模式。不同的非线性振荡模式（包括周期性和混沌性）的出现归因于自然振荡和外部驱动振荡之间的竞争。使用混沌检测方法，如分岔图、相图、首次返回映射和傅里叶谱，仔细研究了周期性和混沌状态之间的转换。作为控制参数的驱动幅度的分岔图显示出了一个有趣而复杂的转换图。
