G phonon linewidth and phonon-phonon interaction in p-type doped CVD graphene crystals

We employed conventional and time-resolved Raman spectroscopy to study the effects of electron-phonon and phonon-phonon interactions on the linewidth of the G phonon in both unintentionally and intentionally doped polycrystalline chemical vapor deposited (CVD) graphene samples. We directly measured the G phonon lifetime, observing a approximate to 14% decrease with doping up to EF = 270 meV. The anticipated reduction of G phonon linewidth due to a decrement in electron-phonon contribution deviates from first principles calculations. CVD samples exhibit a approximate to 30% decrease in the electron-phonon coupling constant, lambda Gamma(EF = 0), compared to exfoliated graphene samples. Additionally, phonon-defect scattering makes a significant contribution to the G band linewidth in CVD graphene samples, owing to their lower crystal quality compared to exfoliated graphene.

Automated summary

We studied the effects of electron-phonon and phonon-phonon interactions on the linewidth of the G phonon in both unintentionally and intentionally doped polycrystalline chemical vapor deposited (CVD) graphene samples using conventional and time-resolved Raman spectroscopy. We found that the lifetime of the G phonon decreased approximately by 14% with increasing doping, contrary to the anticipated reduction in G phonon linewidth due to a decrement in electron-phonon contribution from first principles calculations. The CVD samples exhibited a decrease of approximately 30% in the electron-phonon coupling constant compared to exfoliated graphene samples. Additionally, the contribution of phonon-defect scattering to the G band linewidth was significant in CVD graphene samples due to their lower crystal quality compared to exfoliated graphene.