Ambipolar Field Effect in Topological Insulator Nanoplates of (BixSb1-x)2Te3

TL;DR

This study demonstrates tunable topological insulator nanoplates of (BixSb1-x)2Te3 with ambipolar gating effects, enabling control over bulk and surface conduction for potential nanoelectronic and spintronic applications.

Contribution

It introduces (BixSb1-x)2Te3 nanoplates as a tunable topological insulator system with ambipolar gating, confirmed by ARPES and calculations, advancing topological insulator device integration.

Findings

Confirmed topological insulator behavior across composition range

Demonstrated ambipolar gating effect in nanoplates

Controlled carrier type and concentration in nanostructures

Abstract

Topological insulators represent a new state of quantum matter attractive to both fundamental physics and technological applications such as spintronics and quantum information processing. In a topological insulator, the bulk energy gap is traversed by spin-momentum locked surface states forming an odd number of surface bands that possesses unique electronic properties. However, transport measurements have often been dominated by residual bulk carriers from crystal defects or environmental doping which mask the topological surface contribution. Here we demonstrate (BixSb1-x)2Te3 as a tunable topological insulator system to manipulate bulk conductivity by varying the Bi/Sb composition ratio. (BixSb1-x)2Te3 ternary compounds are confirmed as topological insulators for the entire composition range by angle resolved photoemission spectroscopy (ARPES) measurements and ab initio calculations. Additionally, we observe a clear ambipolar gating effect similar to that observed in graphene using nanoplates of (BixSb1-x)2Te3 in field-effect-transistor (FET) devices. The manipulation of carrier type and concentration in topological insulator nanostructures demonstrated in this study paves the way for implementation of topological insulators in nanoelectronics and spintronics.