Surfactant-Mediated Epitaxial Growth of Single-Layer Graphene in an Unconventional Orientation on SiC

TL;DR

This paper demonstrates a surfactant-assisted method to grow high-quality, uniformly oriented single-layer graphene on SiC with an unconventional $R0^\u00b0$ rotation, enabling potential twisted bilayer graphene applications.

Contribution

It introduces a surfactant-mediated epitaxial growth technique that achieves uniform, high-quality graphene with an unconventional orientation on SiC, surpassing previous template-based methods.

Findings

High-quality, uniform single-layer graphene with $R0^\u00b0$ orientation.

Enhanced crystalline quality and homogeneity over wafer scale.

Potential for epitaxial twisted bilayer graphene via intercalation.

Abstract

We report the use of a surfactant molecule during the epitaxy of graphene on SiC(0001) that leads to the growth in an unconventional orientation, namely $R0^\circ$ rotation with respect to the SiC lattice. It yields a very high-quality single-layer graphene with a uniform orientation with respect to the substrate, on the wafer scale. We find an increased quality and homogeneity compared to the approach based on the use of a pre-oriented template to induce the unconventional orientation. Using spot profile analysis low energy electron diffraction, angle-resolved photoelectron spectroscopy, and the normal incidence x-ray standing wave technique, we assess the crystalline quality and coverage of the graphene layer. Combined with the presence of a covalently-bound graphene layer in the conventional orientation underneath, our surfactant-mediated growth offers an ideal platform to prepare epitaxial twisted bilayer graphene via intercalation.