Ambipolar Surface Conduction in Ternary Topological Insulator Bi_2(Te_{1-x}Se_x)_3 Nanoribbons

TL;DR

This study demonstrates how compositional tuning and gate voltage control in Bi2(Te1-xSex)3 nanoribbons can suppress bulk conduction and enhance surface state contributions, revealing ambipolar surface conduction in a topological insulator.

Contribution

It introduces a method to modulate surface and bulk transport in topological insulator nanoribbons via composition and gating, highlighting ambipolar conduction in thicker samples.

Findings

Se doping suppresses bulk conduction and induces semiconducting behavior.

Gate voltage enables ambipolar modulation of conductance.

Surface states significantly contribute to transport in optimized compositions.

Abstract

We report the composition and gate voltage induced tuning of transport properties in chemically synthesized Bi2(Te1-xSex)3 nanoribbons. It is found that increasing Se concentration effectively suppresses the bulk carrier transport and induces semiconducting behavior in the temperature dependent resistance of Bi2(Te1-xSex)3 nanoribbons when x is greater than ~10%. In Bi2(Te1-xSex)3 nanoribbons with x ~20%, gate voltage enables ambipolar modulation of resistance (or conductance) in samples with thickness around or larger than 100nm, indicating significantly enhanced contribution in transport from the gapless surface states.