Boron nitride substrates for high-quality graphene electronics

Graphene devices on standard SiO 2 substrates are highly disordered, exhibiting characteristics that are far inferior to the expected intrinsic properties of graphene 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 . Although suspending the graphene above the substrate leads to a substantial improvement in device quality 13 , 14 , this geometry imposes severe limitations on device architecture and functionality. There is a growing need, therefore, to identify dielectrics that allow a substrate-supported geometry while retaining the quality achieved with a suspended sample. Hexagonal boron nitride (h-BN) is an appealing substrate, because it has an atomically smooth surface that is relatively free of dangling bonds and charge traps. It also has a lattice constant similar to that of graphite, and has large optical phonon modes and a large electrical bandgap. Here we report the fabrication and characterization of high-quality exfoliated mono- and bilayer graphene devices on single-crystal h-BN substrates, by using a mechanical transfer process. Graphene devices on h-BN substrates have mobilities and carrier inhomogeneities that are almost an order of magnitude better than devices on SiO 2 . These devices also show reduced roughness, intrinsic doping and chemical reactivity. The ability to assemble crystalline layered materials in a controlled way permits the fabrication of graphene devices on other promising dielectrics 15 and allows for the realization of more complex graphene heterostructures. Graphene devices supported on single-crystal hexagonal boron nitride substrates show an enhanced mobility and carrier homogeneity, as well as reduced roughness, intrinsic doping and chemical reactivity, compared with traditional SiO 2 substrates.