We present a detailed Raman study of defective graphene samples containing specific types of defects. In particular, we compared ${\mathit{sp}}^3$ sites, vacancies, and substitutional Boron atoms. We find that the ratio between the $D$ and $G$ peak intensities, $I$($D$)/$I$($G$), does not depend on the geometry of the defect (within the Raman spectrometer resolution). In contrast, in the limit of low defect concentration, the ratio between the $D^{\prime }$ and $G$ peak intensities is higher for vacancies than ${\mathit{sp}}^3$ sites. By using the local activation model, we attribute this difference to the term $C$${}_{S,x}$, representing the Raman cross section of $I$($x$)/$I$($G$) associated with the distortion of the crystal lattice after defect introduction per unit of damaged area, where $x$ $=$ $D$ or $D^{\prime }$. We observed that $C_{S,D}=0$ for all the defects analyzed, while $C_{S,D^{\prime }}$ of vacancies is 2.5 times larger than $C_{S,D^{\prime }}$ of ${\mathit{sp}}^3$ sites. This makes $I$($D$)/$I$($D^{\prime }$) strongly sensitive to the nature of the defect. We also show that the exact dependence of $I$($D$)/$I$($D^{\prime }$) on the excitation energy may be affected by the nature of the defect. These results can be used to obtain further insights into the Raman scattering process (in particular for the $D^{\prime }$ peak) in order to improve our understanding and modeling of defects in graphene.

• Received 11 February 2013

DOI:https://doi.org/10.1103/PhysRevB.88.035426