Ultrathin Topological Insulator Bi2Se3 Nanoribbons Exfoliated by Atomic Force Microscopy

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• 作者：Seung Sae Hong ; Worasom Kundhikanjana ; Judy J. Cha ; Keji Lai ; Desheng Kong ; Stefan Meister ; Michael A. Kelly ; Zhi-Xun Shen ; Yi Cui
• 刊名：Nano Letters
• 出版年：2010
• 出版时间：August 11, 2010
• 年：2010
• 卷：10
• 期：8
• 页码：3118-3122
• 全文大小：383K
• 年卷期：v.10,no.8(August 11, 2010)
• ISSN：1530-6992

文摘

Ultrathin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak van der Waals interaction between adjacent quintuple layers (QLs), the layered bismuth selenide (Bi₂Se₃), a single Dirac-cone topological insulator with a large bulk gap, can be exfoliated down to a few QLs. In this paper, we report the first controlled mechanical exfoliation of Bi₂Se₃ nanoribbons (>50 QLs) by an atomic force microscope (AFM) tip down to a single QL. Microwave impedance microscopy is employed to map out the local conductivity of such ultrathin nanoribbons, showing drastic difference in sheet resistance between 1−2 QLs and 4−5 QLs. Transport measurement carried out on an exfoliated (≤5 QLs) Bi₂Se₃ device shows nonmetallic temperature dependence of resistance, in sharp contrast to the metallic behavior seen in thick (>50 QLs) ribbons. These AFM-exfoliated thin nanoribbons afford interesting candidates for studying the transition from quantum spin Hall surface to edge states.

Keywords:

Topological insulator; bismuth selenide; nanoribbon; mechanical exfoliation; atomic force microscopy