High-frequency coherent phonons in graphene on silicon

Sho Koga, Ikufumi Katayama, Shunsuke Abe, Hirokazu Fukidome, Maki Suemitsu, Masahiro Kitajima, Jun Takeda

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

High-frequency coherent vibrations have been investigated in graphene on silicon substrates using pump-probe anisotropic reflectivity spectroscopy with 7.5fs laser pulses. The coherent phonons of both the intralayer C=C stretching mode (G-mode) and the disorder-induced mode (D-mode) are clearly observed even in monolayer graphenes. The G-mode shifts to higher frequencies as the number of graphene layers decreases, whereas the D-mode does not exhibit such hardening. Moreover, the D-mode softens upon photoexcitation and then shifts to higher frequencies during the relaxation process. The different frequency shift behaviors in the G-and D-modes are discussed.

Original languageEnglish
Article number045101
JournalApplied Physics Express
Volume4
Issue number4
DOIs
Publication statusPublished - 2011 Apr

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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