Charge transfer between epitaxial graphene and silicon carbide

TL;DR

This paper investigates how charge transfer from silicon carbide affects doping levels in epitaxial graphene, analyzing models based on surface and bulk donors, and explores electrostatic gating effects.

Contribution

It introduces two models for charge transfer in epitaxial graphene on SiC and analyzes the maximum doping and gating response in each model.

Findings

Maximum electron density depends on work function differences.

Graphene's responsivity to electrostatic gating varies with doping source.

Charge transfer models predict doping limits in epitaxial graphene.

Abstract

We analyse doping of graphene grown on SiC in two models which differ by the source of charge transfered to graphene, namely, from SiC surface and from bulk donors. For each of the two models, we find the maximum electron density induced in monolayer and bilayer graphene, which is determined by the difference between the work function for electrons in pristine graphene and donor states on/in SiC, and analyse the responsivity of graphene to the density variation by means of electrostatic gates.