Ultrathin Topological Insulator Bi 2 Se 3 Nanoribbons Exfoliated by Atomic Force Microscopy

Seung Sae Hong, Worasom Kundhikanjana, Judy J. Cha, Keji Lai, Desheng Kong, Stefan Meister, Michael A. Kelly, Zhi-Xun Shen, Yi Cui

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141 Scopus citations

Abstract

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 (Bi2Se 3), 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. © 2010 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)3118-3122
Number of pages5
JournalNano Letters
Volume10
Issue number8
DOIs
StatePublished - Aug 11 2010
Externally publishedYes

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