Controlling doping in graphene through a SiC substrate: A first-principles study

TL;DR

This study demonstrates that doping in graphene can be effectively controlled through a silicon carbide substrate, enhancing doping efficiency and reducing scattering, which is promising for graphene-based electronic and magnetic applications.

Contribution

The paper introduces a novel substrate-based doping strategy for graphene, significantly improving doping efficiency and enabling control over magnetic properties without direct impurity doping.

Findings

Doping formation energies decrease by up to 8 eV on SiC substrates.

Charge carrier type and density can be tuned via dopants and passivation.

Epitaxial graphene shows reduced dopant scattering and potential for magnetic property control.

Abstract

Controlling the type and density of charge carriers by doping is the key step for developing graphene electronics. However, direct doping of graphene is rather a challenge. Based on first-principles calculations, a concept of overcoming doping difficulty in graphene via substrate is reported.We find that doping could be strongly enhanced in epitaxial graphene grown on silicon carbide substrate. Compared to free-standing graphene, the formation energies of the dopants can decrease by as much as 8 eV. The type and density of the charge carriers of epitaxial graphene layer can be effectively manipulated by suitable dopants and surface passivation. More importantly, contrasting to the direct doping of graphene, the charge carriers in epitaxial graphene layer are weakly scattered by dopants due to the spatial separation between dopants and the conducting channel. Finally, we show that a similar idea can also be used to control magnetic properties, for example, induce a half-metallic state in the epitaxial graphene without magnetic impurity doping.