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APS » Journals » Phys. Rev. Lett. » Volume 99 » Issue 21
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Phys. Rev. Lett. 99, 216802 (2007) [4 pages]

Biased Bilayer Graphene: Semiconductor with a Gap Tunable by the Electric Field Effect

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Eduardo V. Castro1, K. S. Novoselov2, S. V. Morozov2, N. M. R. Peres3, J. M. B. Lopes dos Santos1, Johan Nilsson4, F. Guinea5, A. K. Geim2, and A. H. Castro Neto4,6
1CFP and Departamento de Física, Faculdade de Ciências Universidade do Porto, P-4169-007 Porto, Portugal
2Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, United Kingdom
3Center of Physics and Departamento de Física, Universidade do Minho, P-4710-057 Braga, Portugal
4Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
5Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain
6Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

Received 15 November 2006; published 20 November 2007

We demonstrate that the electronic gap of a graphene bilayer can be controlled externally by applying a gate bias. From the magnetotransport data (Shubnikov–de Haas measurements of the cyclotron mass), and using a tight-binding model, we extract the value of the gap as a function of the electronic density. We show that the gap can be changed from zero to midinfrared energies by using fields of ≲1  V/nm, below the electric breakdown of SiO2. The opening of a gap is clearly seen in the quantum Hall regime.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.99.216802
DOI:
10.1103/PhysRevLett.99.216802
PACS:
73.20.At, 73.21.Ac, 81.05.Uw
 
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