Doping dependence of the Raman peaks intensity of graphene close to the Dirac point

Here we use pristine graphene samples in order to analyze how the Raman peaks intensity, measured at 2.41 and 1.96 eV excitation energy, changes with the amount of doping. The use of pristine graphene allows investigating the intensity dependence close to the Dirac point. We show that the G peak intensity is independent on the doping, while the 2D peak intensity strongly decreases for increasing doping. Analyzing this dependence in the framework of a fully resonant process, we found that the total electron-phonon scattering rate is similar to 40 meV (60 ps(-1)) at 2.41 eV.