Effect of vacancy defects on phonon properties of hydrogen passivated graphene nanoribbons

M. Sherajul Islam, Satoru Tanaka, Akihiro Hashimoto

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The phonon properties of hydrogen-passivated armchair graphene nanoribbons (AGNRs) with different vacancy concentrations are investigated theoretically. We calculate the change in the phonon density of states (PDOSs) due to a broad range of vacancies and hydrogen passivation effects using forced vibrational method. A large downshift of prominent Raman active U point LO mode phonons with an increase of vacancy concentration or decrease of ribbon widths are observed. We find an increasing peak intensities for the C-H stretching mode with the decrease of ribbon width or the increase of defect density. An inserted vacancy concentration of 10% and higher induce the broadening and distorting of the PDOS peaks significantly. The localization properties of phonon due to defects were also studied. The typical mode pattern of K point iTO mode phonons show the spatial localized vibrations persuaded by armchair edges or vacancies, which are in conceptually good agreement with the large D band of the Raman spectra comes from the armchair-edges or the imperfections of crystal. The typical displacement pattern for C-H stretching mode shows a random displacement of H atoms in contrast to C atoms. Our simulation results show the significant impact of vacancy defects on the vibrational properties of GNRs.

Original languageEnglish
Pages (from-to)146-154
Number of pages9
JournalCarbon
Volume80
Issue number1
DOIs
Publication statusPublished - Jan 1 2014

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)

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