Résumé
In this communication, we will illustrate how Raman spectroscopy can be used tostudy the doping of graphene. We will first report data recorded by in situ Ramanexperiments on single-layer (SLG) graphene during exposure to rubidium vapor. Bythis way, we have been able to follow continuously the changes of the G and 2Dbands features over a broad doping range (up to about 1014 electrons/cm2). Previoustheoretical predictions have shown that the evolution of the G-mode in SLG resultsfrom the competition between adiabatic and non-adiabatic effects. We emphasizethat a possible substrate pinning effect, which inhibits the charge-induced latticeexpansion of graphene layer, can strongly influence the G band position [1].In the second part, we will show that the charge carrier density of grapheneexfoliated on a SiO2/Si substrate can be finely and reversibly tuned between electronand hole doping with visible photons. This photo-induced doping happens undermoderate laser power conditions but is significantly affected by the substratecleaning method. In particular, it requires hydrophilic substrates and vanishes forsuspended graphene. These findings also suggest that Raman spectroscopy is notalways as non-invasive as generally assumed [2].Finally, we will discuss how these results can be useful to extract information aboutgraphene doping and strain from Raman measurements.References[1] R. Parret, M. Paillet, J.-R. Huntzinger, D. Nakabayashi, T. Michel, A. Tiberj, J.-L.Sauvajol, A.-A. Zahab, ACS Nano, 7 (2013) 165.[2] A. Tiberj, M. Rubio-Roy, M. Paillet, J.-R. Huntzinger, P. Landois, M. Mikolasek, S.Contreras, J.-L. Sauvajol, E. Dujardin, A.-A. Zahab, Scientific Reports, 3 (2013)2355.