Growth on metal substrates is a promising route for synthesizing high-quality graphene films. In addition, moving electronic applications into the real world requires understanding and controlling the properties of graphene in contact with metals. This talk will focus on the properties and growth mechanisms on several metals distinguished by varying binding strengths to graphene sheets. Mechanistic insight comes from observing growth directly using low-energy electron microscopy (LEEM). On the relatively strongly interacting substrate Ru(0001), graphene grows with a single in-plane orientation from a highly supersaturated sea of C adatoms. On the less interacting substrates Ir(111) and Pd(111), graphene forms several but discrete in-plane orientations. Small but significant differences in graphene’s electronic properties (i.e., band structure and work function) result from changes in orientation. On Cu foils, graphene islands nucleate with a large range of orientation. Thus, the weak film-Cu interaction leads to a high defect density. Finally, the mechanism of bilayer graphene growth has been explored. Diffraction analysis reveals that the second graphene layer on Ir(111) grows next to the substrate, not on top of the first layer. This “underlayer” growth mechanism occurs when the carbon source is either segregation from the substrate or deposition on top of the first layer. How this unusual mechanism affects thickness uniformity will be discussed.

 

This work was supported by the Office of Basic Energy Sciences, Division of Materials and Engineering Sciences of the U.S. Department of Energy under Contract No. DE-AC04-94AL85000.