Weak mismatch epitaxy and structural feedback in graphene growth on copper foil

Graphene growth by low-pressure chemical vapor deposition on low cost copper
foils shows great promise for large scale applications. It is known that the local
crystallography of the foil influences the graphene growth rate. Here we find an
epitaxial relationship between graphene and copper foil. Interfacial restructuring
between graphene and copper drives the formation of (n10) facets on what is
otherwise a mostly Cu(100) surface, and the facets in turn influence the graphene
orientations from the onset of growth. Angle resolved photoemission shows that
the electronic structure of the graphene is decoupled from the copper indicating
a weak interaction between them. Despite this, two preferred orientations of
graphene are found, ±8° from the Cu[010] direction, creating a non-uniform
distribution of graphene grain boundary misorientation angles. Comparison
with the model system of graphene growth on single crystal Cu(110) indicates
that this orientational alignment is due to mismatch epitaxy. Despite the
differences in symmetry the orientation of the graphene is defined by that of the
copper. We expect these observations to not only have importance for controlling
and understanding the growth process for graphene on copper, but also to have
wider implications for the growth of two-dimensional materials on low cost
metal substrates.