Catalyst-free growth of networked nanographite on Si and SiO2 substrates by photoemission-assisted plasma-enhanced chemical vapor deposition

Tomohide Takami, Shuichi Ogawa, Haruki Sumi, Toshiteru Kaga, Akihiko Saikubo, Eiji Ikenaga, Motonobu Sato, Mizuhisa Nihei, Yuji Takakuwa

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

We have developed a photoemission-assisted plasma-enhanced chemical vapor deposition (CVD) process, where DC discharge plasma is assisted by photoelectrons emitted from the substrate under ultraviolet (UV) light irradiation. Under Ar gas atmosphere and in vacuum, plasma current was measured as a function of sample bias voltage to clarify the mechanism, by which photoemission-assisted plasma is generated. Owing to the advantages of the photoemission-assisted plasma-enhanced CVD, where the plasma is generated close to the substrate and in a controllable volume, we have succeeded in growing shiny black films of networked nanographite, without any catalyst, on Si(001) and SiO2(350 nm)/Si(001) substrates at a deposition rate of ∼2 μm/min despite of low electric power consumption of plasma, ∼4 W. Cross-sectional transmission electron microscopy (TEM) and diffraction (TED) observations revealed that samples grown at ∼700°C with Ar-diluted CH4 were composed of multilayer graphene particles (diameter of ∼10 nm) that were closely connected to each other and shared some grapheme sheets between them, although their crystallographic configurations were randomly oriented. In bulk-sensitive C 1s photoelectron spectra using synchrotron radiation at 7933 eV, a chemically-shifted component of sp 2-bonded carbon atom was dominant and the π-π* transition loss peak was clearly observed for the samples grown on both substrates, indicating that the multilayer graphene particles substantially contain high-quality graphene sheets in agreement with evaluations by microscopic Raman spectroscopy. We named the layered carbon structure "carbon mille-feuille."

Original languageEnglish
Pages (from-to)882-890
Number of pages9
Journale-Journal of Surface Science and Nanotechnology
Volume7
DOIs
Publication statusPublished - 2009 Dec 12

Keywords

  • CVD
  • Catalyst-free
  • DC discharge plasma
  • Multilayer grapheme
  • Photoemission
  • Raman spectroscopy
  • Synchrotron radiation
  • TEM
  • XPS
  • Xe excimer lamp

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Condensed Matter Physics
  • Mechanics of Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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