College of Liberal Arts and Sciences, National University of Defense Technology, Changsha 410073, China.
Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
Phys Rev Lett. 2018 Aug 24;121(8):086806. doi: 10.1103/PhysRevLett.121.086806.
The effect of a coherence resonance is observed experimentally in a GaAs/Al_{0.45}Ga_{0.55}As superlattice under dc bias at room temperature, which is driven by noise. For an applied voltage, for which no current self-oscillations are observed, regular current self-oscillations with a frequency of about 82 MHz are induced by exceeding a certain noise amplitude. In addition, a novel kind of a stochastic resonance is identified, which is triggered by the coherence resonance. This stochastic resonance appears when the device is driven by an external ac signal with a frequency, which is relatively close to that of the regular current self-oscillations at the coherence resonance. The intrinsic oscillation mode in the coherence resonance is found to be phase locked by an extremely weak ac signal. It is demonstrated that an excitable superlattice device can be used for the fast detection of weak signals submerged in noise. These results are very well reproduced by results using numerical simulations based on a sequential resonant tunneling model of nonlinear electron transport in semiconductor superlattices.
室温下，在直流偏置下，通过噪声驱动 GaAs/Al_{0.45}Ga_{0.55}As 超晶格，观察到相干共振的影响。对于施加的电压，如果没有观察到电流自激振荡，则通过超过一定的噪声幅度，可以诱导出具有约 82 MHz 频率的规则电流自激振荡。此外，还确定了一种新的随机共振，它是由相干共振引发的。当器件受到频率与相干共振时规则电流自激振荡相对接近的外部交流信号驱动时，会出现这种随机共振。相干共振中的固有振荡模式被极其微弱的交流信号锁定。结果表明，可激发超晶格器件可用于快速检测淹没在噪声中的弱信号。这些结果与基于半导体超晶格中非线性电子输运的顺序共振隧穿模型的数值模拟结果非常吻合。
