High Quality Graphene Devices in Graphene-Boron Nitride Systems

Graphene, since its first isolation, carries many promises on its superior properties. However, unlike its conventional two-dimensional (2D) counterparts, e.g. Si and GaAs systems, graphene represents the first 2D systems built on an atomically thin structure. With every atoms on the surface, graphene is severely affected by the environment and the measured properties have not reaching its full potential. Avoiding all possible external contamination sources is the key to keep graphene intact and to maintain its high quality electronic properties. To achieve this, it requires a revolution in the graphene device structure engineering, because all factors in a conventional process are scattering sources, i.e. substrate, solvent and polymer residues. With our recent two inventions, i.e. the van der Waals transfer method and the metal-graphene edge-contact, we managed to completely separate the layer assembly and metallization processes. Throughout the entire fabrication process, the graphene layer has never seen any external materials other than hexagonal boron nitride, a perfect substrate for graphene. Both optical and electrical characterizations show our device properties reach the