Silicon carbide stacking-order-induced doping variation in epitaxial graphene

TL;DR

This study reveals that the doping level in epitaxial graphene is influenced by the specific stacking order of silicon carbide (SiC) terraces, enabling nano-scale doping control through substrate patterning.

Contribution

It demonstrates the correlation between SiC surface termination and graphene's electronic properties, introducing a new method for doping engineering via substrate patterning.

Findings

SiC terrace termination affects graphene doping levels

Correlation confirmed by surface-sensitive methods

Proximity effect influences doping variation

Abstract

Generally, it is supposed that the Fermi level in epitaxial graphene is controlled by two effects: p-type polarization doping induced by the bulk of the hexagonal SiC(0001) substrate and overcompensation by donor-like states related to the buffer layer. In this work, we evidence that this effect is also related to the specific underlying SiC terrace. We fabricated a periodic sequence of non-identical SiC terraces, which are unambiguously attributed to specific SiC surface terminations. A clear correlation between the SiC termination and the electronic graphene properties is experimentally observed and confirmed by various complementary surface-sensitive methods. We attribute this correlation to a proximity effect of the SiC termination-dependent polarization doping on the overlying graphene layer. Our findings open a new approach for a nano-scale doping-engineering by self-patterning of epitaxial graphene and other 2D layers on dielectric polar substrates.