Bulk-Induced 1/f Noise at the Surface of Three-Dimensional Topological Insulators.
Bulk-Induced 1/f Noise at the Surface of Three-Dimensional Topological Insulators.
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DOI：
10.1021/acsnano.5b06163
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发表时间：
2015-11
期刊：
影响因子：
17.1
通讯作者：
S. Bhattacharyya;Mitali Banerjee;H. Nhalil;Saurav Islam;C. Dasgupta;S. Elizabeth;A. Ghosh
中科院分区：
文献类型：
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作者：
S. Bhattacharyya;Mitali Banerjee;H. Nhalil;Saurav Islam;C. Dasgupta;S. Elizabeth;A. Ghosh
在强拓扑绝缘体（TI）的表面输运中，缓慢的固有电阻波动（也称为闪烁噪声或1/f噪声）是一种知之甚少的现象。在这里，我们已经系统地探讨了1/f噪声场效应晶体管（FET）的机械剥离的Bi 1.6Sb 0.4Te 2Se TI薄膜时，运输主要通过表面状态发生。我们发现，缓慢的动力学的大部分TI内的电荷紊乱诱导迁移率波动的表面，提供了一个新的来源的固有的1/f噪声是唯一的散装TI系统。当沟道厚度较小时，噪声幅值可以非常小，对应的Hooge参数γH可低至10 μ m（-4），但当沟道厚度超过10 μm时，噪声幅值迅速增大。从噪声的温度（T）的依赖性，它显示在特征值的T尖锐的峰值，我们确定了代复合过程从带间跃迁内的TI体的迁移率波动的主要来源，在表面运输。我们的实验不仅建立了一个内在的微观来源的噪声在TI表面通道，但也揭示了一个独特的光谱信息的杂质带，可以在散装TI系统一般是有用的。
Slow intrinsic fluctuations of resistance, also known as the flicker noise or 1/f-noise, in the surface transport of strong topological insulators (TIs) is a poorly understood phenomenon. Here, we have systematically explored the 1/f-noise in field-effect transistors (FET) of mechanically exfoliated Bi1.6Sb0.4Te2Se TI films when transport occurs predominantly via the surface states. We find that the slow kinetics of the charge disorder within the bulk of the TI induces mobility fluctuations at the surface, providing a new source of intrinsic 1/f-noise that is unique to bulk TI systems. At small channel thickness, the noise magnitude can be extremely small, corresponding to the phenomenological Hooge parameter γH as low as ≈10(-4), but it increases rapidly when channel thickness exceeds ∼1 μm. From the temperature (T)-dependence of noise, which displayed sharp peaks at characteristic values of T, we identified generation-recombination processes from interband transitions within the TI bulk as the dominant source of the mobility fluctuations in surface transport. Our experiment not only establishes an intrinsic microscopic origin of noise in TI surface channels, but also reveals a unique spectroscopic information on the impurity bands that can be useful in bulk TI systems in general.