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Tunable excitons in biased bilayer graphene

Cited 76 time in Web of Science Cited 80 time in Scopus
Authors

Park, Cheol-Hwan; Louie, Steven G.

Issue Date
2010-02
Publisher
American Chemical Society
Citation
Nano Letters, Vol.10 No.2, pp.426-431
Abstract
Recent measurements have shown that a continuously tunable bandgap of up to 250 meV can be generated in biased bilayer graphene [Zhang. Y.; et al. Nature 2009, 459, 820], opening up pathway for possible graphene-based nanoelectronic and nanophotonic devices operating at room temperature. Here, we show that the optical response of this system is dominated by bound excitons. The main feature of the optical absorbance spectrum is determined by a single symmetric peak arising from excitons, a profile that is markedly different from that of an lnterband transition picture. Under laboratory conditions, the binding energy of the excitons may be tuned with the external bias going from zero to several tens of millielectronvolts. These novel strong excitonic behaviors result from a peculiar, effective "one-dimensional" joint density of states and a continuously tunable bandgap in biased bilayer graphene. Moreover, we show that the electronic structure (level degeneracy, optical selection rules, etc.) of the bound excitons in a biased bilayer graphene is markedly different from that of a two-dimensional hydrogen atom because of the pseudospin physics. © 2010 American Chemical Society.
ISSN
1530-6984
URI
https://hdl.handle.net/10371/202364
DOI
https://doi.org/10.1021/nl902932k
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  • College of Natural Sciences
  • Department of Physics and Astronomy
Research Area Condensed Matter Physics, Nanoscale Photonics, Nanoscale Physics, 나노 물리와 나노 광자학, 응집 물질 물리

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