Insights into the early growth of homogeneous single-layer graphene over NI-MO binary substrates

The employment of Ni-Mo films has recently been shown to yield strictly homogeneous single-layer graphene. In this study, we systematically investigate the different stages of nucleation and growth of graphene over Ni-Mo layers. The studies reveal that the Ni film breaks up and diffuses into the underlying Mo foil, forming a Ni-Mo intermetallic. Nucleation only occurs from Ni sites, and thus, the nucleation density can be controlled by the Ni film thickness. Both nucleation and growth of the graphene are shown to be susceptible to very efficient self-termination processes to the formation of molybdenum carbide, and this guarantees the formation of large area graphene that consists entirely of monolayer graphene. © 2013 American Chemical Society.115181sciescopu