Probing the Intrinsic Properties of Exfoliated Graphene: Raman Spectroscopy of Free-Standing Monolayers - Condensed Matter > Materials ScienceReport as inadecuate




Probing the Intrinsic Properties of Exfoliated Graphene: Raman Spectroscopy of Free-Standing Monolayers - Condensed Matter > Materials Science - Download this document for free, or read online. Document in PDF available to download.

Abstract: The properties of pristine, free-standing graphene monolayers prepared bymechanical exfoliation of graphite are investigated. The graphene monolayers,suspended over open trenches, are examined by means of spatially resolved Ramanspectroscopy of the G-, D-, and 2D-phonon modes. The G-mode phonons exhibitreduced energies 1580 cm-1 and increased widths 14 cm-1 compared to theresponse of graphene monolayers supported on the SiO2 covered substrate. Fromanalysis of the G-mode Raman spectra, we deduce that the free-standing graphenemonolayers are essentially undoped, with an upper bound of 2x10^11 cm-2 for theresidual carrier concentration. On the supported regions, significantly higherand spatially inhomogeneous doping is observed. The free-standing graphenemonolayers show little local disorder, based on the very weak Raman D-moderesponse. The two-phonon 2D mode of the free-standing graphene monolayers isdownshifted in frequency compared to that of the supported region of thesamples and exhibits a narrowed, positively skewed line shape.



Author: Stephane Berciaud, Sunmin Ryu, Louis E. Brus, Tony F. Heinz

Source: https://arxiv.org/







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