Raman Excitation Profile of the G-band Enhancement in Twisted Bilayer Graphene

G. S.N. Eliel, H. B. Ribeiro, K. Sato, R. Saito, Chun Chieh Lu, Po Wen Chiu, C. Fantini, A. Righi, M. A. Pimenta

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5 Citations (Scopus)

Abstract

A resonant Raman study of twisted bilayer graphene (TBG) samples with different twisting angles using many different laser lines in the visible range is presented. The samples were fabricated by CVD technique and transferred to Si/SiO2 substrates. The Raman excitation profiles of the huge enhancement of the G-band intensity for a group of different TBG flakes were obtained experimentally, and the analysis of the profiles using a theoretical expression for the Raman intensities allowed us to obtain the energies of the van Hove singularities generated by the Moiré patterns and the lifetimes of the excited state of the Raman process. Our results exhibit a good agreement between experimental and calculated energies for van Hove singularities and show that the lifetime of photoexcited carrier does not depend significantly on the twisting angle in the range intermediate angles (between 10 and 15). We observed that the width of the resonance window (Γ ≈ 250 meV) is much larger than the REP of the Raman modes of carbon nanotubes, which are also enhanced by resonances with van Hove singularities.

Original languageEnglish
Pages (from-to)589-593
Number of pages5
JournalBrazilian Journal of Physics
Volume47
Issue number6
DOIs
Publication statusPublished - 2017 Dec 1

Keywords

  • Moiré pattern
  • Resonance Raman spectroscopy
  • Twisted bilayer graphene

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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