Few layer epitaxial graphenes (1.8–3.0 layers) grown on vicinal 6H–SiC (0001) were characterized by deep ultraviolet Raman spectroscopy. Shallow penetration depth of the probe laser enabled us to observe G-peak of graphene without subtraction of the SiC substrate signal from observed spectra. The G-peak was greatly shifted to higher frequency compared to that of graphite due to in-plane compressive stress deriving from the substrate. The frequency shift decreased with the number of graphene layers because of stress relaxation from layer to layer. Our experiment suggests that the stress is completely relaxed within five to six graphene layers.
REFERENCES
1.
R. P.
Wallace
, Phys. Rev.
71
, 622
(1947
).2.
N.
Hamada
, S. -I.
Sawada
, and A.
Oshiyama
, Phys. Rev. Lett.
68
, 1579
(1992
).3.
K. S.
Novoselov
, A. K.
Geim
, S. V.
Morozov
, D.
Jiang
, M. I.
Katsnelson
, I. V.
Grigorieva
, S. V.
Dubonos
, and A. A.
Firov
, Science
306
, 666
(2004
).4.
A. K.
Geim
and K. S.
Novoselov
, Nature Mater.
6
, 183
(2007
), and references therein.5.
A. K.
Geim
, Science
324
, 1530
(2009
), and references therein.6.
T.
Seyller
, A.
Bostwick
, K. V.
Emtsev
, K.
Horn
, L.
Ley
, J. L.
McChesney
, T.
Ohta
, J. D.
Riley
, E.
Rotenberg
, and F.
Speck
, Phys. Status Solidi B
245
, 1436
(2008
).7.
J.
Hass
, W. A.
de Heer
, and E. H.
Conrad
, J. Phys.: Condens. Matter
20
, 323202
(2008
).8.
A. C.
Ferrari
, J. C.
Meyer
, V.
Scardaci
, C.
Casiraghi
, M.
Lazzeri
, F.
Muri
, S.
Piscanec
, D.
Jiang
, K. S.
Novoselev
, S.
Roth
, and A. K.
Geim
, Phys. Rev. Lett.
97
, 187401
(2006
).9.
L. M.
Malard
, M. A.
Pimenta
, G.
Dresselhaus
, and M. S.
Dresselhaus
, Phys. Rep.
473
, 51
(2009
).10.
J.
Röhrl
, M.
Hundhausen
, K. V.
Emtsev
, T.
Seyler
, R.
Graupner
, and L.
Ley
, Appl. Phys. Lett.
92
, 201918
(2008
).11.
C.
Faugeras
, A.
Nerriere
, M.
Potemski
, A.
Mahmood
, E.
Dujardin
, C.
Berger
, and W. A.
de Heer
, Appl. Phys. Lett.
92
, 011914
(2008
).12.
D. S.
Lee
, C.
Riedl
, B.
Kraus
, K.
von Klitzing
, U.
Starke
, and J. H.
Smet
, Nano Lett.
8
, 4320
(2008
).13.
Z. H.
Ni
, W.
Chen
, X. F.
Fan
, J. L.
Kuo
, T.
Yu
, A. T. S.
Wee
, and Z. X.
Shen
, Phys. Rev. B
77
, 115416
(2008
).14.
N.
Ferralis
, R.
Maboudian
, and C.
Carraro
, Phys. Rev. Lett.
101
, 156801
(2008
).15.
S.
Tanaka
, K.
Morita
, and H.
Hibino
, Phys. Rev. B
81
, 041406
(R) (2010
).16.
17.
S.
Adachi
, Optical Constants of Crystalline and Amorphous Semiconductors Numerical Data and Graphical Information
(Springer
, Berlin
, 1999
).18.
D. K. L.
Tsang
, B. J.
Marsden
, and A. S.
Fok
, Carbon
43
, 2902
(2005
).19.
M.
Stockmeier
, S. A.
Saker
, P.
Hens
, P. J.
Wellmann
, R.
Hock
, and A.
Magerl
, Mater. Sci. Forum
600–603
, 517
(2009
).20.
A.
Ferrari
and J.
Robertson
, Phys. Rev. B
61
, 14095
(2000
).21.
J.
Röhrl
, M.
Hundhausen
, K. V.
Emtsev
, T.
Seyler
, R.
Graupner
, and L.
Ley
, Mater. Sci. Forum
645–648
, 603
(2010
).22.
D.
Graf
, F.
Molitor
, K.
Ensslin
, C.
Stampfer
, A.
Jungen
, C.
Hierold
, and L.
Wiltz
, Nano Lett.
7
, 238
(2007
).23.
I.
Calizo
, I.
Bejenari
, M.
Rahman
, G.
Liu
, and A. A.
Balandin
, J. Appl. Phys.
106
, 043509
(2009
).© 2010 American Institute of Physics.
2010
American Institute of Physics
You do not currently have access to this content.
