Nonlocal Chemical Potential Modulation in Topological Insulators Enabled by Highly Mobile Trapped Charges,ACS Applied Electronic Materials

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Nonlocal Chemical Potential Modulation in Topological Insulators Enabled by Highly Mobile Trapped Charges
ACS Applied Electronic Materials ( IF 4.3 ) Pub Date : 2020-09-23 , DOI: 10.1021/acsaelm.0c00701
Yasen Hou ₁ , Rui Xiao ₁ , Senlei Li ₁ , Lang Wang ₁ , Dong Yu ₁

Affiliation

Topological insulators (TIs) host unusual surface states with Dirac dispersion and helical spin texture and hold high potential for applications in spintronics and quantum computing. However, unintentional doping due to native defects in these materials creates a key obstacle to displaying their desired unique spin and charge transport properties. Here, we report a simple and effective method that can in situ tune the chemical potential in Bi_2–xSb_xSe₃ nanoribbon devices, with a magnitude significantly larger than traditional electrostatic gating. An electric field parallel to a device channel alters the chemical potential both in the channel and out of the channel. We demonstrate that such modulation is enabled by fast charge diffusion among defect states, further visualized by photocurrent mapping. Our observations enable dynamic chemical potential engineering, providing tremendous opportunities for investigating fundamental transport mechanisms of charge and composite particles, such as excitons, in TIs.

中文翻译：

高度移动的陷阱电荷在拓扑绝缘子中实现非本地化学势调制

拓扑绝缘体（TI）具有Dirac色散和螺旋自旋纹理的异常表面状态，在自旋电子学和量子计算中具有很高的应用潜力。然而，由于这些材料中的固有缺陷而导致的无意掺杂对显示其所需的独特自旋和电荷传输性质造成了关键障碍。在这里，我们报告了一种简单有效的方法，可以原位调整Bi _{2– x} Sb _x Se _3中的化学势纳米带器件，其幅度明显大于传统的静电门控。平行于设备通道的电场会改变通道内和通道外的化学势。我们证明了这种调制是通过缺陷状态之间的快速电荷扩散实现的，进一步通过光电流映射将其可视化。我们的观察使动态化学势工程成为可能，为研究TI中电荷和复合粒子（例如激子）的基本传输机制提供了巨大的机会。

更新日期：2020-10-28

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