分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-03-27
Zhizhen Yin
Helun Song
Yaohui Zhang
Miguel Ruiz-García
Manuel Carretero
Luis L. Bonilla
Klaus Biermann
Holger T. Grahn
摘要： Noise-enhanced chaos in a doped, weakly coupled GaAs/Al0.45Ga0.55As superlattice has been observed at room temperature in experiments as well as in the results of the simulation of nonlinear transport based on a discrete tunneling model. When external noise is added, both the measured and simulated current-versus-time traces contain irregularly spaced spikes for particular applied voltages, which separate a regime of periodic current oscillations from a region of no current oscillations at all. In the voltage region without current oscillations, the electric-field profile consist of a low-field domain near the emitter contact separated by a domain wall consisting of a charge accumulation layer from a high-field regime closer to the collector contact. With increasing noise amplitude, spontaneous chaotic current oscillations appear over a wider bias voltage range. For these bias voltages, the domain boundary between the two electric-field domains becomes unstable and very small current or voltage fluctuations can trigger the domain boundary to move toward the collector and induce chaotic current spikes. The experimentally observed features are qualitatively very well reproduced by the simulations. Increased noise can consequently enhance chaotic current oscillations in semiconductor superlattices.
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