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

TL;DR

This paper demonstrates surface state dominated transport in Sb-doped Bi2Se3 nanoribbons with ultra-low bulk carrier concentrations, enabling better exploration of topological insulator properties and potential applications.

Contribution

It reports the achievement of the lowest bulk carrier concentration in 3D topological insulators and demonstrates control of surface states near the Dirac point in nanoribbons.

Findings

Achieved bulk electron concentration as low as 2x10^11/cm2.

Controlled surface states near the Dirac point in nanoribbons.

Demonstrated surface-dominant transport in ultra-thin nanoribbons.

Abstract

A topological insulator is a new state of 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 via electron transport measurement. Here we report surface state dominated transport in Sb-doped Bi2Se3 nanoribbons with very low bulk electron concentrations. In the nanoribbons with sub-10nm thickness protected by a ZnO layer, we demonstrate complete control of their top and bottom surfaces near the Dirac point, achieving the lowest carrier concentration of 2x10^11/cm2 reported in three-dimensional (3D) topological insulators. The Sb-doped Bi2Se3 nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications.