Department of Applied Physics, Stanford University, 476 Lomita Mall, McCullough 343, Stanford, California 94305, USA.
Nat Commun. 2012 Mar 27;3:757. doi: 10.1038/ncomms1771.
A topological insulator is the state of quantum matter possessing gapless spin-locking surface states across the bulk band gap, which has created new opportunities from novel electronics to energy conversion. However, the large concentration of bulk residual carriers has been a major challenge for revealing the property of the topological surface state by electron transport measurements. Here we report the surface-state-dominant transport in antimony-doped, zinc oxide-encapsulated Bi(2)Se(3) nanoribbons with suppressed bulk electron concentration. In the nanoribbon with sub-10-nm thickness protected by a zinc oxide layer, we position the Fermi levels of the top and bottom surfaces near the Dirac point by electrostatic gating, achieving extremely low two-dimensional carrier concentration of 2×10(11) cm(-2). The zinc oxide-capped, antimony-doped Bi(2)Se(3) nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications.
拓扑绝缘体是一种量子物质状态，具有贯穿体带隙的无能隙自旋锁定表面态，这为从新型电子学到能量转换创造了新的机会。然而，体残余载流子的高浓度一直是通过电子输运测量揭示拓扑表面态性质的主要挑战。在这里，我们报告了在受抑制的体电子浓度下，掺杂锑的、氧化锌包裹的 Bi(2)Se(3)纳米带中以表面态为主的输运。在氧化锌层保护的厚度小于 10nm 的纳米带中，我们通过静电门控将上下表面的费米能级置于狄拉克点附近，实现了极低的二维载流子浓度 2×10(11)cm(-2)。氧化锌覆盖的、掺杂锑的 Bi(2)Se(3)纳米结构为研究拓扑绝缘体中的基础物理以及未来的应用提供了一个有吸引力的材料平台。
