It looks likes your graphene is multilayer (above 1000 layers). Maybe not properly exfoliated

I synthesis it through CVD method and then transfer it on the si subtrate Can you please tell me about this weired peak at around 2400

You should typically not get this peak ~2400 as it is not analogous to graphene or Si. It is probably some contamination (maybe PMMA residues). Recheck your CVD processing method. You can also do EDX for your prepared graphene to know what this impurity might be (if its not carbon-related).

Faisal Latif

The observed spectra are attributed to overtones of CH, NH, and OH stretches and combinations of the stretches and angle deformations; the region between 700 and 1600 nm is typically assigned to overtones (14,300–6250 cm-1), and the region between 1600 and 2500 nm to combinations (6250–4000 cm-1). Because there is only one photon, the symmetry of the sum of the vibrations has to be compatible with the odd character of the electric field. That would imply, for instance, that a combination of a symmetric and asymmetric XH vibrations would occur in the "overtone" region. It should be noted that the longer-wavelength detectors that are sensitive to the combination region are noisier and more expensive (in the case of the multichannel arrays this is quite significant) than the shorter-wavelength detectors that can measure overtones. .

Fran Adar is the Worldwide Raman Applications Manager for Horiba Jobin Yvon (Edison, New Jersey). She can be reached by e-mail at [email protected].

Elemental mapping techniques using TEM or EDAX analysis apart from Raman Spectroscopy analysis can also be employed to know the exact name of the peaks in the Graphene sample..