Intercalation of few-layer graphite flakes with FeCl3: Raman determination of Fermi level, layer by layer decoupling, and stability.
Tan, Ping Heng
J Am Chem Soc
American Chemical Society (ACS)
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Zhao, W., Tan, P. H., Liu, J., & Ferrari, A. (2011). Intercalation of few-layer graphite flakes with FeCl3: Raman determination of Fermi level, layer by layer decoupling, and stability.. J Am Chem Soc, 133 (15), 5941-5946. https://doi.org/10.1021/ja110939a
We use anhydrous ferric chloride (FeCl(3)) to intercalate graphite flakes consisting of 2-4 graphene layers and to dope graphene monolayers. The intercalant, staging, stability, and doping of the resulting intercalation compounds (ICs) are characterized by Raman scattering. The G peak of heavily doped monolayer graphene upshifts to ∼1627 cm(-1). The 2-4 layer ICs have similar upshifts, and a Lorentzian line shape for the 2D band, indicating that each layer behaves as a decoupled heavily doped monolayer. By performing Raman measurements at different excitation energies, we show that, for a given doping level, the 2D peak can be suppressed by Pauli blocking for laser energy below the doping level. Thus, multiwavelength Raman spectroscopy allows a direct measurement of the Fermi level, complementary to that derived by performing measurements at fixed excitation energy significantly higher than the doping level. This allows us to estimate a Fermi level shift of up to ∼0.9 eV. These ICs are thus ideal test-beds for the physical and chemical properties of heavily doped graphenes.
Engineering and Physical Sciences Research Council (EP/G042357/1)
External DOI: https://doi.org/10.1021/ja110939a
This record's URL: https://www.repository.cam.ac.uk/handle/1810/286121