Thermodynamic equilibrium conditions of graphene films on SiC

TL;DR

This study uses first-principles calculations to determine the thermodynamic stability of graphene films on SiC, providing insights into optimal conditions for high-quality graphene growth.

Contribution

It introduces a detailed thermodynamic phase diagram for graphene on SiC based on van der Waals corrected DFT, considering full supercell geometries.

Findings

Epitaxial monolayer graphene can be thermodynamically stable under specific conditions.

Full supercell models are essential for accurate interface stability predictions.

Provides a pathway to optimize growth conditions for high-quality graphene.

Abstract

First-principles surface phase diagrams reveal that epitaxial monolayer graphene films on the Si side of 3C-SiC(111) can exist as thermodynamically stable phases in a narrow range of experimentally controllable conditions, defining a path to the highest-quality graphene films. Our calculations are based on a van der Waals corrected density functional. The full, experimentally observed (6 sqrt(3)x 6 sqrt(3))-R30 supercells for zero- to trilayer graphene are essential to describe the correct interface geometries and the relative stability of surface phases and possible defects.