Fermi Level Tuning of Epitaxial Sb2Te3 Thin Films on Graphene by Regulating Intrinsic Defects and Substrate Transfer Doping

TL;DR

This study demonstrates precise Fermi level tuning of epitaxial Sb2Te3 thin films on graphene by controlling intrinsic defects and substrate doping, enabling exploration of topological insulator properties.

Contribution

It introduces a method to tune the Fermi level of Sb2Te3 films via defect control and substrate doping, advancing topological insulator research.

Findings

Fermi level can be tuned across the entire bulk band gap.

Intrinsic defects are identified as Sb vacancies and SbTe antisites.

Defect minimization combined with substrate doping enables Fermi level control.

Abstract

High-quality Sb2Te3 films are obtained by molecular beam epitaxy on graphene substrate and investigated by in situ scanning tunneling microscopy/spectroscopy. Intrinsic defects responsible for the natural p-type conductivity of Sb2Te3 are identified to be the Sb vacancies and SbTe antisites in agreement with first-principles calculations. By minimizing defect densities, coupled with a transfer doping by the graphene substrate, the Fermi level of Sb2Te3 thin films can be tuned over the entire range of the bulk band gap. This establishes the necessary condition to explore topological insulator behaviors near the Dirac point.