2009/05/31 by Kin Fai Mak, Chun Hung Lui, Jie Shan +1 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.102.256405
10 pages, 4 figures, Phys. Rev. Lett. 102, 256405
arxiv created 2009/08/03 · arxiv updated 2015/05/13
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 ~ 1 V/nm is applied by an electrolyte gate to the bilayer system, inducing a carrier density of about 1013 cm-2. 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.