Focused-ion-beam-assisted selective control of graphene layers: acquisition of clean-cut ultra thin graphitic film.

A focused-ion beam (FIB) and a nanomanipulator provide a novel way to selectively control and obtain a few layers of graphene. Because of its weak van der Waals force in the interlayer of graphite, the nanomanipulator could easily exfoliate a graphitic thin layer with no wrinkles on the surface from a highly oriented pyrolitic graphite (HOPG) by applying a shear force which exceeds the static interlayer shear force. Subsequently, a few layers of graphene were successfully obtained by applying a uniform shear force from a detached graphitic thin layer that had been transferred to a pre-determined site on an oxide wafer. The required shear force for clean cleavage of a graphitic thin layer was then estimated based upon experimental data. Raman scattering analysis was used to confirm the number of placed graphene layers and the placement of a few layers of graphene was projected to have about five atomic layers.