No abstract

We fabricated artificially stacked double-layer graphene by sequentially transferring graphene grown by chemical vapor deposition. The double-layer graphene was characterized by Raman spectroscopy and transport measurements. A weak localization effect was observed for different charge carrier densities and temperatures. The obtained intervalley scattering rate was unusually high compared to normal Bernal-stacked bilayer or single-layer graphene. The sharp point defects, local deformation, or bending of graphene plane required for intervalley scattering from one Dirac cone to another seemed to be enhanced by the artificially stacked graphene layers.

We report on the measurements of nonlinear current-voltage characteristics of graphene fabricated by chemical vapor deposition. The current-voltage characteristic is described by a power law with a superlinear dependence of the current on the voltage, and the nonlinearity depends on the carrier density and the excitation level. The nonlinearity is strongest at the Dirac point and becomes weaker as the carrier density increases. At the Dirac point, we also observe a crossover to a much stronger nonlinear transport when the electric field increases above 104 V/m.

We report on the measurements of electronic transport properties of CVD graphene placed on a pre-patterned substrate with periodic nano trenches. A strong anisotropy has been observed between the transport parallel and perpendicular to the trenches. Characteristically different weak localization corrections have been also observed when the transport was perpendicular to the trench, which is interpreted as due to a density inhomogeneity generated by the potential modulations.