Raman Spectra of Monolayer and Multilayer Graphene 07300190007

Raman Spectra of Monolayer and Multilayer Graphene 07300190007 蔺楠 Tutors: 马世红 & 白翠琴 Collaborators: 姚思嘉 & 尹伊伦

• What is Graphene ? A. K. Geim & P. Kim Scientific American(2008) A. H. Neto et al. Rev Mod Phys(2009)

• How to get Graphene? • Micromechanical cleavage • CVD (Chemical vapor-phase deposition) • K. S. Novoselov et al. Science(2004)

• How to find Graphene? • What can be seen under the optical microscope? • Si+Si. O 2 (300 nm)as wafer A. K. Geim & P. Kim Scientific American(2008)

Raman spectrum Ratio of Intensities=1. 45: 1: 4. 55 FWHM=28. 49 cm-1

Change of 2 D peak and G peak of samples of different colors Change of position for 2 D peak >2%(50 cm-1) Change of position for G peak ~4 cm-1 Ratio of the height of two peaks

Split of 2 D peak Two Lorentzian peak fit 0. 6 & 0. 99 V. S. 0. 25 & 0. 5 Ferrari, A. C. et al. PRL 97, 187401(2006)

• G peak • E 2 g mode optical phonon band at Center of BZ( ) Ferrari, A. C. et al. PRB 20, 392(1979)

2 D peak Double-resonance Raman Process Ferrari, A. C. et al. PRL 97, 187401(2006)

Split of 2 D peak for bilayer Graphene Malard, L. M. et al. PRB 76, 201401(2007)

Summary • Observation of Raman spectrum of Graphene with different layers • The position of G peak is the same for layers larger than 1. • The intensity of G peak increases with the number of layers • Observation of different shape, position, intensity of 2 D peak between monolayer and mutilayer Graphene. • Need AFM or STM to identify the number of layers.

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