Reliably counting atomic planes of few-layer graphene (n > 4)

Yee Kan Koh, Myung Ho Bae, David G. Cahill, Eric Pop

Research output: Contribution to journalArticlepeer-review


We demonstrate a reliable technique for counting atomic planes (n) of few-layer graphene (FLG) on SiO2/Si substrates by Raman spectroscopy. Our approach is based on measuring the ratio of the integrated intensity of the G graphene peak and the optical phonon peak of Si, I(G)/I(Si), and is particularly useful in the range n > 4 where few methods exist. We compare our results with atomic force microscopy (AFM) measurements and Fresnel equation calculations. Then, we apply our method to unambiguously identify n of FLG devices on SiO2 and find that the mobility (μ ≈ 2000 cm 2 V-1 s-1) is independent of layer thickness for n > 4. Our findings suggest that electrical transport in gated FLG devices is dominated by carriers near the FLG/SiO2 interface and is thus limited by the environment, even for n > 4.

Original languageEnglish (US)
Pages (from-to)269-274
Number of pages6
JournalACS Nano
Issue number1
StatePublished - Jan 25 2011


  • Absorbance of monolayer graphene
  • Electrostatic interlayer screening
  • Few-layer graphene
  • Field-effect mobility of carriers
  • Graphene thickness
  • Number of graphene layers
  • Raman spectroscopy

ASJC Scopus subject areas

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


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