Bandgap opening in graphene templates on Ru(0001) from subsurface hydrogen effects studied by STM, LEED, and DFT*

Graphene has aroused tremendous interest due to its remarkable electronic and mechanical properties. Graphene's optical properties, conductance, and the fact that it can be transferred to many substrates make it an ideal candidate for use in nanoelectronic devices and organic photoelectric devices. The lack of a bandgap, however, causes a serious challenge for implementing graphene as a material for electrical switches and therefore creative ways of inducing this bandgap are needed. We will present a STM/LEED/DFT study of the single layer graphene on Ru(0001) system in the presence of hydrogen. Structural studies show arrays of moir\'e superlattices with sizes ranging from 0.9 to 3.0 nm in the presence of hydrogen on the compact surface of ruthenium. First principle calculations help explain the appearance of these arrays of graphene reconstructions driven by the H presence at the Ru(0001) interface, and furthermore, predict the appearance of a bandgap with values correlated with the moir\'e superstructure sizes in the presence of hydrogen. Control over moir\'e superstructure size can aid in future work using graphene as a nanotemplate for self assembled growth of nanoelectronic devices an organic photovoltaics.