Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Abstract Epigraphene, which is graphene that is epitaxially grown on a single crystal silicon carbide (SiC) substrate, was proposed as a path to extend Moore’s roadmap beyond silicon at the beginning of the millennium. Despite considerable progress, the lack of a bandgap in graphene and steps on the substrate continued to be roadblocks. Here we show a new method to produce millimeter scale step-free terraces covered with a graphene-like interface that is bonded to the SiC surface. This so-called buffer layer is found to be two-dimensional semiconducting epigraphene (SEG) with a 0.6 eV bandgap and a room temperature mobility exceeding 4000 cm 2 V -1 s -1 , which surpasses all current 2D single layer semiconductors by a factor of 10. A top-gated SEG field-effect transistor demonstrates an on-to-off ratio of 10 4 which is suitable for digital electronics. In addition, we also find that hydrogen intercalation converts SEG into a high-mobility semi-metallic epigraphene monolayer that can be seamlessly integrated with SEG. Centimeter scale mean free paths are observed in the epigraphene edge state of this quasi-freestanding monolayer, which is by a factor of 1000, the largest room temperature electronic mean free path observed in any material.