An experimental study of Raman scattering in N-layer graphene as a function of the top layer doping is reported. At high doping level, achieved by a CHF3 plasma treatment, we observe a splitting of the G band in the spectra of bilayer and 4-layer graphene (N even), whereas the splitting is not visible in case of monolayer and trilayer graphene (N odd). The different behaviors are related to distinct electron-phonon interactions, which are affected by symmetry breaking and Fermi-level position in different ways in the various N-layer graphenes. In trilayer graphene, a weakening of the electron-phonon coupling as a function of the Fermi energy induces a hardening of all zone-center in-plane optical-phonon modes, such as in monolayer graphene. On the other hand, in 4-layer graphene two distinct trends are observed in the G band as a function of doping, suggesting the presence of two different groups of electron-phonon interactions, such as in bilayer graphene.
Observation of Raman G-band splitting in top-doped few-layer graphene / Bruna, Matteo; Borini, Stefano Marco. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 81:(2010). [10.1103/PhysRevB.81.125421]
|Titolo:||Observation of Raman G-band splitting in top-doped few-layer graphene|
|Data di pubblicazione:||2010|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1103/PhysRevB.81.125421|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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