We report on measurements of the quantum capacitance in graphene as a function of charge carrier density. A resonant LC-circuit giving high sensitivity to small capacitance changes is employed. The density of states, which is directly proportional to the quantum capacitance, is found to be significantly larger than zero at and around the charge neutrality point. This finding is interpreted to be a result of potential fluctuations with amplitudes of the order of 100 meV in good agreement with scanning single-electron transistor measurements on bulk graphene and transport studies on nanoribbons.

1.
T. P.
Smith
,
B. B.
Goldber
,
P. J.
Stiles
, and
M.
Heiblum
,
Phys. Rev. B
32
,
2696
(
1985
) and references 6–12 therein.
2.
F.
Stern
,
Appl. Phys. Lett.
43
,
974
(
1983
).
3.
S.
Ilani
,
L. A. K.
Donev
,
M.
Kindermann
, and
P. L.
McEuen
,
Nat. Phys.
2
,
687
(
2006
).
4.
T.
Fang
,
A.
Konar
,
H.
Xing
, and
D.
Jenaa
,
Appl. Phys. Lett.
91
,
092109
(
2007
).
5.
A. A.
Shylau
,
J. W.
Klos
, and
I. V.
Zozoulenko
, arXiv:0907.1040 (
2009
).
6.
Z.
Chen
, and
J.
Appenzeller
,
Tech. Dig. - Int. Electron Devices Meet.
2008
,
509
.
7.
J.
Xia
,
F.
Chen
,
J.
Li
, and
N.
Tao
,
Nat. Nanotechnol.
4
,
505
(
2009
).
8.
J.
Martin
,
N.
Akerman
,
G.
Ulbricht
,
T.
Lohmann
,
J. H.
Smet
,
K.
von Klitzing
, and
A.
Yacoby
,
Nat. Phys.
4
,
144
(
2008
).
9.
K. S.
Novoselov
,
A. K.
Geim
,
S. V.
Morozov
,
D.
Jiang
,
Y.
Zhang
,
S. V.
Dubonos
,
I. V.
Grigorieva
, and
A. A.
Firsov
,
Science
306
,
666
(
2004
).
10.
A. C.
Ferrari
,
J. C.
Meyer
,
V.
Scardaci
,
C.
Casiraghi
,
M.
Lazzeri
,
F.
Mauri
,
S.
Piscanec
,
D.
Jiang
,
K. S.
Novoselov
,
S.
Roth
, and
A. K.
Geim
,
Phys. Rev. Lett.
97
,
187401
(
2006
).
11.
D.
Graf
,
F.
Molitor
,
K.
Ensslin
,
C.
Stampfer
,
A.
Jungen
,
C.
Hierold
, and
L.
Wirtz
,
Nano Lett.
7
,
238
(
2007
).
12.
D. S.
Sivia
and
J.
Skilling
,
Data analysis: A Bayesian Tutorial
(
Oxford University Press
,
2006
).
13.
P. R.
Wallace
,
Phys. Rev.
71
,
622
(
1947
).
14.
C.
Stampfer
,
J.
Güttinger
,
S.
Hellmüller
,
F.
Molitor
,
K.
Ensslin
, and
T.
Ihn
,
Phys. Rev. Lett.
102
,
056403
(
2009
).
15.
F.
Molitor
,
A.
Jacobsen
,
C.
Stampfer
,
J.
Güttinger
,
T.
Ihn
, and
K.
Ensslin
,
Phys. Rev. B
79
,
075426
(
2009
).
16.
K.
Todd
,
H. T.
Chou
,
A.
Amasha
, and
D.
Goldhaber-Gordon
,
Nano Lett.
9
,
416
(
2009
).
17.
X.
Liu
,
J. B.
Oostinga
,
A. F.
Morpurgo
, and
L. M. K.
Vandersypen
,
Phys. Rev. B
80
,
121407
(
2009
).
18.
M. Y.
Han
,
J. C.
Brant
, and
P.
Kim
, arXiv:0910.4808 (
2009
).
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