Model and Simulations of the Epitaxial Growth of Graphene on Non-Planar 6H-SiC Surfaces

TL;DR

This paper models the epitaxial growth of graphene on 6H-SiC surfaces using kinetic Monte Carlo simulations, revealing how nano-facets fracture and how their morphology relates to growth parameters.

Contribution

It introduces a kinetic Monte Carlo model for graphene growth on non-planar SiC surfaces, linking nano-facet fracture behavior to surface morphology and growth barriers.

Findings

Nano-facet fracture into multiple facets during growth.

Fracture angle distribution varies with terrace propagation barrier.

Model enables extraction of energy barriers from experimental data.

Abstract

We study step flow growth of epitaxial graphene on 6H-SiC using a one dimensional kinetic Monte Carlo model. The model parameters are effective energy barriers for the nucleation and propagation of graphene at the SiC steps. When the model is applied to graphene growth on vicinal surfaces, a strip width distribution is used to characterize the surface morphology. Additional kinetic processes are included to study graphene growth on SiC nano-facets. Our main result is that the original nano-facet is fractured into several nano-facets during graphene growth. This phenomenon is characterized by the angle at which the fractured nano-facet is oriented with respect to the basal plane. The distribution of this angle across the surface is found to be related to the strip width distribution for vicinal surfaces. As the terrace propagation barrier decreases, the fracture angle distribution changes continously from two-sided Gaussian to one-sided power-law. Using this distribution, it will be possible to extract energy barriers from experiments and interpret the growth morphology quantitatively.