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Ultrathin epitaxial graphite: 2D electron gas properties and a route toward graphene-based nanoelectronics

Claire Berger·Zhimin Song·Tianbo Li·Xuebin Li·Asmerom Y. Ogbazghi·Rui Feng·Zhenting Dai·Alexei N. Marchenkov·Edward H. Conrad·Phillip N. First·Walt A. de Heer
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Abstract

We have produced ultrathin epitaxial graphite films which show remarkable 2D electron gas (2DEG) behavior. The films, composed of typically 3 graphene sheets, were grown by thermal decomposition on the (0001) surface of 6H-SiC, and characterized by surface-science techniques. The low-temperature conductance spans a range of localization regimes according to the structural state (square resistance 1.5 kOhm to 225 kOhm at 4 K, with positive magnetoconductance). Low resistance samples show characteristics of weak-localization in two dimensions, from which we estimate elastic and inelastic mean free paths. At low field, the Hall resistance is linear up to 4.5 T, which is well-explained by n-type carriers of density 10^{12} cm^{-2} per graphene sheet. The most highly-ordered sample exhibits Shubnikov - de Haas oscillations which correspond to nonlinearities observed in the Hall resistance, indicating a potential new quantum Hall system. We show that the high-mobility films can be patterned via conventional lithographic techniques, and we demonstrate modulation of the film conductance using a top-gate electrode. These key elements suggest electronic device applications based on nano-patterned epitaxial graphene (NPEG), with the potential for large-scale integration.

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Claire Berger, Zhimin Song, Tianbo Li, Xuebin Li, Asmerom Y. Ogbazghi, Rui Feng, Zhenting Dai, Alexei N. Marchenkov, Edward H. Conrad, Phillip N. First, Walt A. de Heer. 2004-10-10. Ultrathin epitaxial graphite: 2D electron gas properties and a route toward graphene-based nanoelectronics. https://doi.org/10.1021/jp040650f

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