Evolution of the Raman spectra from single-, few-, and many-layer graphene with increasing disorder

We report on the micro-Raman spectroscopy of monolayer, bilayer, trilayer, and many layers of graphene (graphite) bombarded by low-energy argon ions with different doses. The evolution of peak frequencies, intensities, linewidths, and areas of the main Raman bands of graphene is analyzed as function of the distance between defects and number of layers. We describe the disorder-induced frequency shifts and the increase in the linewidth of the Raman bands by means of a spatial-correlation model. Also, the evolution of the relative areas A(D)/A(G), A(D')/A(G), and A(G')/A(G) is described by a phenomenological model. The present results can be used to fully characterize disorder in graphene systems.