Pronounced quantum hall-effect on epitaxial graphene up to 70K
Mechanical exfoliated graphene, a monolayer of carbon atoms tightly packed into a two-dimensional (2D) hexagonal lattice, has recently been shown to be thermodynamically stable and exhibits astonishing transport properties, such as an electron mobility of ~15,000 cm2/Vs and an electron velocity of ~108 cm/s at room temperature. However, this exfoliation process cannot form the basis for a large-scale manufacturing process. Recent reports of large-area epitaxial graphene by thermal decomposition of SiC wafers have provided the missing pathway to a viable electronics technology. An interesting question that remains to be addressed is whether the electrical properties of epitaxial graphene on SiC are essentially same as those in exfoliated graphene films. For example, the well-known quantum Hall-effect (QHE), a distinguishing feature of a 2D electronic material system, is just beginning to be discovered in epitaxial graphene. In this paper, we report on the observation of the QHE in gated epitaxial graphene films on SiC (0001), along with pronounced Shubnikov-de Haas (SdH) oscillations in magnetotransport. The last QH plateau is especially pronounced, even at temperatures as high as 70K, reaching the temperature limit of the present experimental setup.