  We use low-energy electron microscopy to investigate how graphene grows on
Cu(111). Graphene islands first nucleate at substrate defects such as step
bunches and impurities. A considerable fraction of these islands can be
rotationally misaligned with the substrate, generating grain boundaries upon
interisland impingement. New rotational boundaries are also generated as
graphene grows across substrate step bunches. Thus, rougher substrates lead to
higher degrees of mosaicity than do flatter substrates. Increasing the growth
temperature improves crystallographic alignment. We demonstrate that graphene
growth on Cu(111) is surface diffusion limited by comparing simulations of the
time evolution of island shapes with experiments. Islands are dendritic with
distinct lobes, but unlike the polycrystalline, four-lobed islands observed on
(100)-textured Cu foils, each island can be a single crystal. Thus, epitaxial
graphene on smooth, clean Cu(111) has fewer structural defects than it does on
Cu(100).
