Formation of Epitaxial Graphene on SiC(0001) using Vacuum or Argon Environments

TL;DR

This study investigates the formation of epitaxial graphene on SiC(0001) in vacuum and argon environments, revealing temperature-dependent growth mechanisms, surface step dynamics, and secondary phase formation.

Contribution

It provides new insights into how environmental conditions affect graphene growth on SiC, including temperature thresholds and surface morphology changes.

Findings

Graphene forms at ~1400°C in vacuum and ~1600°C in argon.

Surface step motion leads to step bunching and layer-by-layer growth.

Disordered graphitic phase appears on the graphene surface.

Abstract

The formation of graphene on the (0001) surface of SiC (the Si-face) is studied by atomic force microscopy, low-energy electron microscopy, and scanning tunneling microscopy/spectroscopy. The graphene forms due to preferential sublimation of Si from the surface at high temperature, and the formation has been studied in both high-vacuum and 1-atm-argon environments. In vacuum, a few monolayers of graphene forms at temperatures around 1400 C, whereas in argon a temperature of about 1600 C is required in order to obtain a single graphene monolayer. In both cases considerable step motion on the surface is observed, with the resulting formation of step bunches separated laterally by >10 microns. Between the step bunches, layer-by-layer growth of the graphene is found. The presence of a disordered, secondary graphitic phase on the surface of the graphene is also identified.