  As undesirable defects, grain boundaries (GBs) are widespread in epitaxial
graphene using existing growth methods on metal substrates. Employing density
functional theory calculations, we first identify that the misorientations of
carbon islands nucleated on a Cu(111) surface lead to the formation of GBs as
the islands coalesce. We then propose a two-step kinetic pathway to effectively
suppress the formation of GBs. In the first step, large aromatic hydrocarbon
molecules are deposited onto a $\sqrt{3}\times\sqrt{3}$ superstructured Cu-Mn
alloyed surface to seed the initial carbon clusters of a single orientation; in
the second step, the seeded islands are enlarged through normal chemical vapor
deposition of methane to form a complete graphene sheet. The present approach
promises to overcome a standing obstacle in large scale single-crystal graphene
fabrication.

Materials Science