‘Graphene-on-insulator’ fabricated on atomically controlled solid surfaces

Abstract

Graphene or few layer graphene (FLG) was attached on a single-crystalline sapphire surface on which a regularly ordered step/terrace structure was formed. The height of graphene from the substrate surface was observed to be about 0.35 nm, which is almost equal to the layer spacing of graphite. On the attached graphene or FLG surface, the step/terrace structure originating from the sapphire surface was clearly observed because the graphene flake tightly adhered to the sapphire surface. FLGs were etched by a reaction between carbon of the FLG and H2 gas at 900 °C using Fe nanoparticles as catalysts. When a FLG flake is thick, the etching direction is subject to the crystallographic directions of graphene. As the FLG is thinner than 6 nm, strain induced on the FLG surface by the step/terrace structure of the substrate surface influences the etching direction, and etching along a buried step occurs when the Fe nanoparticle size is small. The etching directions of FLG can be controlled by the ordered atomic step arrangement on sapphire surfaces owing to the surface flatness and tight adhesion of graphene to the surface.