Observation of an Electric-Field-Induced Band Gap in Bilayer Graphene by Infrared Spectroscopy

Kin Fai Mak, Chun Hung Lui, Jie Shan, and Tony F. Heinz
Phys. Rev. Lett. 102, 256405 – Published 26 June 2009


It has been predicted that application of a strong electric field perpendicular to the plane of bilayer graphene can induce a significant band gap. We have measured the optical conductivity of bilayer graphene with an efficient electrolyte top gate for a photon energy range of 0.2–0.7 eV. We see the emergence of new transitions as a band gap opens. A band gap approaching 200 meV is observed when an electric field 1V/nm is applied, inducing a carrier density of about 1013cm2. The magnitude of the band gap and the features observed in the infrared conductivity spectra are broadly compatible with calculations within a tight-binding model.

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  • Received 1 May 2009


©2009 American Physical Society

Authors & Affiliations

Kin Fai Mak1, Chun Hung Lui1, Jie Shan2, and Tony F. Heinz1,*

  • 1Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA
  • 2Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA

  • *Corresponding author: tony.heinz@columbia.edu

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Vol. 102, Iss. 25 — 26 June 2009

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