We show the evolution of Raman spectra with a number of graphene layers on different substrates, SiO2/Si and conducting indium tin oxide (ITO) plate. The 𝐺 mode peak position and the intensity ratio of 𝐺 and 2𝐷 bands depend on the preparation of sample for the same number of graphene layers. The 2𝐷 Raman band has characteristic line shapes in single and bilayer graphene, capturing the differences in their electronic structure. The defects have a significant influence on the 𝐺 band peak position for the single layer graphene: the frequency shows a blue shift up to 12 cm-1 depending on the intensity of the 𝐷 Raman band, which is a marker of the defect density. Most surprisingly, Raman spectra of graphene on the conducting ITO plates show a lowering of the 𝐺 mode frequency by ∼ 6 cm-1 and the 2𝐷 band frequency by ∼ 20 cm-1. This red-shift of the 𝐺 and 2𝐷 bands is observed for the first time in single layer graphene.
Volume 43, 2020
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