Tuning Many-Body Interactions in Graphene: The Effects of Doping on Excitons and Carrier Lifetimes

The optical properties of graphene are strongly affected by electron-electron (e-e) and electron-hole (e-h) interactions. Here we tune these many-body interactions through varying the density of free charge carriers. Measurements from the infrared to the ultraviolet reveal significant changes in the...

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Bibliographic Details
Published in:Physical review letters 2014-05, Vol.112 (20), Article 207401
Main Authors: Mak, Kin Fai, da Jornada, Felipe H., He, Keliang, Deslippe, Jack, Petrone, Nicholas, Hone, James, Shan, Jie, Louie, Steven G., Heinz, Tony F.
Format: Article
Language:English
Subjects:
Carriers
Density
Doping
Excitons
Graphene
Infrared
Optical properties
Tuning
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Summary:The optical properties of graphene are strongly affected by electron-electron (e-e) and electron-hole (e-h) interactions. Here we tune these many-body interactions through varying the density of free charge carriers. Measurements from the infrared to the ultraviolet reveal significant changes in the optical conductivity of graphene for both electron and hole doping. The shift, broadening, and modification in shape of the saddle-point exciton resonance reflect strong screening of the many-body interactions by the carriers, as well as changes in quasiparticle lifetimes. Ab initio calculations by the GW Bethe-Salpeter equation method, which take into account the modification of both the repulsive e-e and the attractive e-h interactions, provide excellent agreement with experiment. Understanding the optical properties and high-energy carrier dynamics of graphene over a wide range of doping is crucial for both fundamental graphene physics and for emerging applications of graphene in photonics.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.112.207401