Dear Shivani,
Attached please find a chapter that discusses this topic. I have copied an important paragraph related to your question. From the paragraph it can be concluded the ratio D/G is decreased since G is increased while D is decreased upon doping.
Characterization of edges is not only useful in differentiating between zigzag
and armchair, but also in characterizing the grain boundaries of CVD graphene
crystals. Where grains from two separate seed points grow together, a boundary
forms that is identifiable through an increased D peak, providing insight into the
crystal growth process. The nucleation center of these crystals is also
characterized by a higher D peak [43].
Doping in graphene, which shifts the Fermi level away from the Dirac point,
decreases the probability of excited charge carrier recombination [44]. This causes photon perturbations to be non-adiabatic, removing the Kohn anomaly and increasing the phonon energy for the G peak, increasing its frequency [45]. This reduced recombination also sharpens the G peak, decreasing its FWHM. Das et al also theorize increased electron concentration (decreased hole concentration) expands the crystal lattice, decreasing the energy of the Raman phonons, resulting in a decreased 2D peak position with increased electron concentration and an asymmetry in the doping effect of the G peak position. Doping graphene also decreases the intensity of the 2D peak.
Hoping this will be helpful,
Rafik
Dear Shivani,
Attached please find a chapter that discusses this topic. I have copied an important paragraph related to your question. From the paragraph it can be concluded the ratio D/G is decreased since G is increased while D is decreased upon doping.
Characterization of edges is not only useful in differentiating between zigzag
and armchair, but also in characterizing the grain boundaries of CVD graphene
crystals. Where grains from two separate seed points grow together, a boundary
forms that is identifiable through an increased D peak, providing insight into the
crystal growth process. The nucleation center of these crystals is also
characterized by a higher D peak [43].
Doping in graphene, which shifts the Fermi level away from the Dirac point,
decreases the probability of excited charge carrier recombination [44]. This causes photon perturbations to be non-adiabatic, removing the Kohn anomaly and increasing the phonon energy for the G peak, increasing its frequency [45]. This reduced recombination also sharpens the G peak, decreasing its FWHM. Das et al also theorize increased electron concentration (decreased hole concentration) expands the crystal lattice, decreasing the energy of the Raman phonons, resulting in a decreased 2D peak position with increased electron concentration and an asymmetry in the doping effect of the G peak position. Doping graphene also decreases the intensity of the 2D peak.
Hoping this will be helpful,
Rafik
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