Graphene-to-substrate energy transfer through out-of-plane longitudinal acoustic phonons

I. Ju Chen, Pierre Adrien Mante, Cheng Kai Chang, Szu Chi Yang, Hui Yuan Chen, Yu Ru Huang, Li Chyong Chen, Kuei Hsien Chen, Vitalyi Gusev, Chi Kuang Sun

Research output: Journal article publicationJournal articleAcademic researchpeer-review

19 Citations (Scopus)

Abstract

Practically, graphene is often deposited on substrates. Given the major substrate-induced modification of properties and considerable energy transfer at the interface, the graphene-substrate interaction has been widely discussed. However, the proposed mechanisms were restricted to the two-dimensional (2D) plane and interface, while the energy conduction in the third dimension is hardly considered. Herein, we disclose the transfer of energy perpendicular to the interface of the combined system of the 2D graphene and the 3D base. More precisely, our observation of the energy dissipation of optically excited graphene via emitting out-of-plane longitudinal acoustic phonon into the substrate is presented. By applying nanoultrasonic spectroscopy with a piezoelectric nanolayer embedded in the substrate, we found that under photoexcitation by a femtosecond laser pulse graphene can emit longitudinal coherent acoustic phonons (CAPs) with frequencies over 1 THz into the substrate. In addition, the waveform of the CAP pulse infers that the photocarriers and sudden lattice heating in graphene caused modification of graphene-substrate bond and consequently generated longitudinal acoustic phonons in the substrate. The direct observation of this unexplored graphene-to-substrate vertical energy transfer channel can bring new insights into the understanding of the energy dissipation and limited transport properties of supported graphene.

Original languageEnglish
Pages (from-to)1317-1323
Number of pages7
JournalNano Letters
Volume14
Issue number3
DOIs
Publication statusPublished - 12 Mar 2014
Externally publishedYes

Keywords

  • Graphene
  • nanoultrasonic spectroscopy
  • picosecond ultrasonics
  • substrate effect
  • THz coherent acoustic phonon

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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