We present a detailed Raman study of defective graphene samples containing
specific types of defects. In particular, we compared sp3 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′ and G peak intensities is
higher for vacancies than sp3 sites. By using the local activation model, we
attribute this difference to the term CS,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′. We
observed that CS,D=0 for all the defects analyzed, while CS,D′ of vacancies is
2.5 times larger than CS,D′ of sp3 sites. This makes I(D)/I(D′) strongly
sensitive to the nature of the defect. We also show that the exact dependence
of I(D)/I(D′) 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′ peak) in order to improve our
understanding and modeling of defects in graphene
