Evolution in Surface Morphology of Epitaxial Graphene Layers on SiC Induced by Controlled Structural Strain

TL;DR

This study investigates how controlled structural strain influences the surface morphology evolution of epitaxial graphene layers on SiC substrates, revealing the effects of annealing time on film stress and roughness.

Contribution

It provides new insights into how annealing duration affects internal stress and surface morphology in epitaxial graphene on SiC, highlighting the role of controlled strain.

Findings

Long annealing increases surface roughness and induces compressive stress.

Short annealing maintains minimal morphological changes and results in stress-free films.

Growth temperature determines film thickness, while annealing time influences stress and morphology.

Abstract

The evolution in the surface morphology of epitaxial graphene films and 6H-SiC(0001) substrates is studied by electron channeling contrast imaging. Whereas film thickness is determined by growth temperature only, increasing growth times at constant temperature affect both internal stress and film morphology. Annealing times in excess of 8-10 minutes lead to an increase in the mean square roughness of SiC step edges to which graphene films are pinned, resulting in compressively stressed films at room temperature. Shorter annealing times produce minimal changes in the morphology of the terrace edges and result in nearly stress-free films upon cooling to room temperature.