Strong phonon-plasmon coupled modes in the graphene/silicon carbide heterosystem

R. J. Koch; Th. Seyller; J. A. Schaefer

doi:10.1103/PhysRevB.82.201413

paper

Strong phonon-plasmon coupled modes in the graphene/silicon carbide heterosystem

arXiv:1008.1130 · doi:10.1103/PhysRevB.82.201413

Abstract

We report on strong coupling of the charge carrier plasmon $ω_{P L}$ in graphene with the surface optical phonon $ω_{S O}$ of the underlying SiC(0001) substrate with low electron concentration ( $n = 1.2 \times 1 0^{15}$ $c m^{- 3}$ ) in the long wavelength limit ( $q_{∥} \to 0$ ). Energy dependent energy-loss spectra give for the first time clear evidence of two coupled phonon-plasmon modes $ω_{\pm}$ separated by a gap between $ω_{S O}$ ( $q_{∥} \to 0$ ) and $ω_{T O}$ ( $q_{∥} >> 0$ ), the transverse optical phonon mode, with a Fano-type shape, in particular for higher primary electron energies ( $E_{0} \geq 20 e V$ ). A simplified model based on dielectric theory is able to simulate our energy - loss spectra as well as the dispersion of the two coupled phonon-plasmon modes $ω_{\pm}$ . In contrast, Liu and Willis [1] postulate in their recent publication no gap and a discontinuous dispersion curve with a one-peak structure from their energy-loss data.

arXiv comment4 pages, 3 figures, presented during Graphene Week 2010, Maryland University, College Park, Maryland, USA, April 19-23, 2010

Strong phonon-plasmon coupled modes in the graphene/silicon carbide heterosystem

Abstract

References in corpus (6)

Cited by in corpus (42)