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 language | English (US) |
|---|---|
| Pages (from-to) | 3118-3122 |
| Number of pages | 5 |
| Journal | Nano Letters |
| Volume | 10 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 11 2010 |
| Externally published | Yes |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): KUS-11-001-12, KUS-FI-033-02
Acknowledgements: Y.C. acknowledges the support from the Keck Foundation. This work is also made possible by the King Abdullah University of Science and Technology (KAUST) Investigator Award (No. KUS-11-001-12) and KAUST GRP Fellowship (No. KUS-FI-033-02), NSF Grant DMR-0906027, and Center of Probing the Nanoscale, Stanford University (NSF Grant PHY-0425897)
This publication acknowledges KAUST support, but has no KAUST affiliated authors.