Ultrathin Epitaxial Graphite:  2D Electron Gas Properties and a Route toward Graphene-based Nanoelectronics

Abstract

We have produced ultrathin epitaxial graphite films which show remarkable 2D\nelectron gas (2DEG) behavior. The films, composed of typically 3 graphene\nsheets, were grown by thermal decomposition on the (0001) surface of 6H-SiC,\nand characterized by surface-science techniques. The low-temperature\nconductance spans a range of localization regimes according to the structural\nstate (square resistance 1.5 kOhm to 225 kOhm at 4 K, with positive\nmagnetoconductance). Low resistance samples show characteristics of\nweak-localization in two dimensions, from which we estimate elastic and\ninelastic mean free paths. At low field, the Hall resistance is linear up to\n4.5 T, which is well-explained by n-type carriers of density 10^{12} cm^{-2}\nper graphene sheet. The most highly-ordered sample exhibits Shubnikov - de Haas\noscillations which correspond to nonlinearities observed in the Hall\nresistance, indicating a potential new quantum Hall system. We show that the\nhigh-mobility films can be patterned via conventional lithographic techniques,\nand we demonstrate modulation of the film conductance using a top-gate\nelectrode. These key elements suggest electronic device applications based on\nnano-patterned epitaxial graphene (NPEG), with the potential for large-scale\nintegration.\n

Keywords

Affiliated Institutions

• Georgia Institute of Technology US

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