Atomic Hole Doping of Graphene

TL;DR

This paper demonstrates that atomic doping with bismuth, antimony, or gold effectively induces p-type doping in epitaxial graphene on SiC, enabling precise control of charge carriers without disrupting its band structure.

Contribution

It introduces a reliable atomic doping method for graphene using specific elements, overcoming previous challenges with chemical doping techniques.

Findings

Atomic doping with Bi, Sb, or Au induces p-type behavior.

Charge carrier type can be tuned from electrons to holes.

Band structure remains intact after doping.

Abstract

Graphene is an excellent candidate for the next generation of electronic materials due to the strict two-dimensionality of its electronic structure as well as the extremely high carrier mobility. A prerequisite for the development of graphene based electronics is the reliable control of the type and density of the charge carriers by external (gate) and internal (doping) means. While gating has been successfully demonstrated for graphene flakes and epitaxial graphene on silicon carbide, the development of reliable chemical doping methods turns out to be a real challenge. In particular hole doping is an unsolved issue. So far it has only been achieved with reactive molecular adsorbates, which are largely incompatible with any device technology. Here we show by angle-resolved photoemission spectroscopy that atomic doping of an epitaxial graphene layer on a silicon carbide substrate with bismuth, antimony or gold presents effective means of p-type doping. Not only is the atomic doping the method of choice for the internal control of the carrier density. In combination with the intrinsic n-type character of epitaxial graphene on SiC, the charge carriers can be tuned from electrons to holes, without affecting the conical band structure.