Ultra-low carrier concentration and surface-dominant transport in antimony-doped Bi₂Se₃ topological insulator nanoribbons

摘要

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 Bi₂Se₃ 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 2×1011 cm?2. The zinc oxide-capped, antimony-doped Bi₂Se₃ nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications.. ? 2012 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.