Breit-Wigner-Fano line shapes in Raman spectra of graphene

Excitation of electron-hole pairs in the vicinity of the Dirac cone by the Coulomb interaction gives rise to an asymmetric Breit-Wigner-Fano line shape in the phonon Raman spectra in graphene. This asymmetric line shape appears due to the interference effect between the phonon spectra and the electron-hole pair excitation spectra. The calculated Breit-Wigner-Fano asymmetric factor 1/q(BWF) as a function of the Fermi energy shows a V-shaped curve with a minimum value at the charge neutrality point and gives good agreement with the experimental results.