The origin of sub-bands in the Raman D-band of graphene
In Raman spectroscopy investigations of defective suspended graphene, splitting in the D band is observed. Four double resonance Raman scattering processes: the outer and inner scattering processes, as well as the scattering processes with electrons first scattered by phonons (“phonon-first”) or by...
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| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2013
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| Online Access: | https://hdl.handle.net/10356/95988 http://hdl.handle.net/10220/10809 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | In Raman spectroscopy investigations of defective suspended graphene, splitting in the D band is observed. Four double resonance Raman scattering processes: the outer and inner scattering processes, as well as the scattering processes with electrons first scattered by phonons (“phonon-first”) or by defects (“defect-first”), are found to be responsible for these features of the D band. The D sub-bands associated with the outer and inner processes merge with increasing defect concentration. However a Stokes/anti-Stokes Raman study indicates that the splitting of the D band due to the separate “phonon-first” and “defect-first” processes is valid for suspended graphene. For graphene samples on a SiO2/Si substrate, the sub-bands of D band merge due to the increased Raman broadening parameter resulting from the substrate doping. Moreover, the merging of the sub-bands shows excitation energy dependence, which can be understood by considering the energy dependent lifetime and/or scattering rate of photo-excited carriers in the Raman scattering process. |
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