Raman scattering from high-frequency phonons in supported n-graphene layer films

A. Gupta, G. Chen, P. Joshi, S. Tadigadapa, P. C. Eklund

Research output: Contribution to journalArticlepeer-review

1223 Scopus citations

Abstract

Results of room-temperature Raman scattering studies of ultrathin graphitic films supported on Si (100)/SiO2 substrates are reported. The results are significantly different from those known for graphite. Spectra were collected using 514.5 nm radiation on films containing from n = 1 to 20 graphene layers, as determined by atomic force microscopy. Both the first- and second-order Raman spectra show unique signatures of the number of layers in the film. The nGL film analogue of the Raman G-band in graphite exhibits a Lorentzian line shape whose center frequency shifts linearly relative to graphite as ∼1/n (for n = 1 ωG ≈ 1587 cm-1). Three weak bands, identified with disorder-induced first-order scattering, are observed at ∼1350, 1450, and 1500 cm-1. The ∼1500 cm -1 band is weak but relatively sharp and exhibits an interesting n-dependence. in general, the intensity of these D-bands decreases dramatically with increasing n. Three second-order bands are also observed (∼2450, ∼2700, and 3248 cm-1). They are analogues to those observed in graphite. However, the ∼2700 cm-1 band exhibits an interesting and dramatic change of shape with n. Interestingly, for n < 5 this second-order band is more intense than the G-band.

Original languageEnglish (US)
Pages (from-to)2667-2673
Number of pages7
JournalNano letters
Volume6
Issue number12
DOIs
StatePublished - Dec 2006

All Science Journal Classification (ASJC) codes

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

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