Slow gold adatom diffusion on graphene: effect of silicon dioxide and hexagonal boron nitride substrates.

We examine the nucleation kinetics of Au clusters on graphene and explore the relationship with layer number and underlying supporting substrate of graphene. Using the mean field theory of diffusion-limited aggregation, morphology patterns are semiquantitatively analyzed to obtain Au adatom effective diffusion constants and activation energies. Under specified assumptions, the Au adatom diffusion constant for single-layer graphene supported on SiO2 is ∼50 times smaller than that for hexagonal boron nitride (h-BN)-supported graphene and on the order of 800 times smaller than that for multilayer graphite.

Scanning tunneling microscopy and X-ray photoelectron spectroscopy studies of graphene films prepared by sonication-assisted dispersion.

We describe scanning tunneling microscopy and X-ray photoelectron spectroscopy studies of graphene films produced by sonication-assisted dispersion. Defects in these samples are not randomly distributed, and the graphene films exhibit a "patchwork" structure where unperturbed graphene areas are adjacent to heavily functionalized ones. Adjacent graphene layers are likely in poor mechanical contact due to adventitious species trapped between the carbon sheets of the sample.