We present a simple shadow mask method to fabricate electrodes with nanometer scale separation. Metal wires with gaps are made by incorporating multiwall carbon nanotubes or single-wall carbon nanotube (SWNT) bundles into a trilayer electron beam lithography process. The simple, highly controllable, and scaleable method has been used to make gaps with widths between 20 and 100 nm and may be extended to gap sizes of 1 nm. We report electron transport measurements of individual SWNTs bridging nanogaps with electrode spacings of approximately 20 nm. Metallic SWNTs exhibit quantum dot behavior with an 80 meV charging energy and a 20 meV energy level splitting. We observe a strong field effect behavior in short semiconducting SWNT segments, evidence for diffusive electron transport in these samples.

1.
A.
Bezryadin
,
C.
Dekker
, and
G.
Schmid
,
Appl. Phys. Lett.
71
,
1273
(
1997
).
2.
C. J.
Muller
,
J. M.
van Ruitenbeek
, and
L. J.
de Jongh
,
Phys. Rev. Lett.
69
,
140
(
1992
).
3.
A.
Bezryadin
and
C.
Dekker
,
J. Vac. Sci. Technol. B
15
,
793
(
1997
).
4.
A. F.
Morpurgo
,
C. M.
Marcus
, and
D. B.
Robinson
,
Appl. Phys. Lett.
74
,
1933
(
1999
).
5.
H.
Park
,
A. K. L.
Kim
,
A. P.
Alivisatos
,
J.
Park
, and
P. L.
McEuen
,
Appl. Phys. Lett.
75
,
151
(
1999
).
6.
G. J.
Dolan
,
Appl. Phys. Lett.
31
,
337
(
1977
).
7.
For review, see M. S. Dresselhaus, G. Dresselhaus, and P. C. Eklund, Science of Fullerenes and Carbon Nanotubes (Academic, San Diego, 1996).
8.
S.
Iijima
,
Nature (London)
354
,
56
(
1991
).
9.
A.
Thess
,
R.
Lee
,
P.
Nikolaev
,
H. J.
Dai
,
P.
Petit
,
J.
Robert
,
C. H.
Xu
,
Y. H.
Lee
,
S. G.
Kim
,
A. G.
Rinzler
,
D. T.
Colbert
,
G. E.
Scuseria
,
D.
Tomanek
,
J. E.
Fischer
, and
R. E.
Smalley
,
Science
273
,
482
(
1996
).
10.
S. J.
Tans
,
M. H.
Devoret
,
H. J.
Dai
,
A.
Thess
,
R. E.
Smalley
,
L. J.
Geerligs
, and
C.
Dekker
,
Nature (London)
386
,
474
(
1997
);
M.
Bockrath
,
D. H.
Cobden
,
P. L.
McEuen
,
N. G.
Chopra
,
A.
Zettl
,
A.
Thess
, and
R. E.
Smalley
,
Science
275
,
1922
(
1997
).
11.
S. J.
Tans
,
A. R. M.
Verschueuren
, and
C.
Dekker
,
Nature (London)
393
,
49
(
1998
).
12.
R.
Martel
,
T.
Schmidt
,
H. R.
Shea
,
T.
Hertel
, and
P.
Avouris
,
Appl. Phys. Lett.
73
,
2447
(
1998
).
13.
R. D.
Antonov
and
A. T.
Johnson
,
Phys. Rev. Lett.
83
,
3274
(
1999
).
14.
L. C.
Venema
,
J. W. G.
Wildoer
,
J. W.
Janssen
,
S. J.
Tans
,
H. L. J. T.
Tuinstra
,
L. P.
Kouwenhoven
, and
C.
Dekker
,
Science
283
,
52
(
1999
).
15.
R. D. Antonov, Ph.D. thesis, University of Pennsylvania, 1999 (unpublished).
16.
A.
Bezryadin
,
A. R. M.
Verschueren
,
S. J.
Tans
, and
C.
Dekker
,
Phys. Rev. Lett.
80
,
4036
(
1998
).
17.
The charging energy of a short nanotube segment is taken to be U=e2/8εL, with ε=2.5ε0 and L the length of the nanotube. The zero-dimensional level spacing is ΔE=hVF/4L including both band and spin degeneracy, with VF=8×105m/s.
18.
The charging energy of a long nanotube segment is taken to be U=e2ln(2h/r)/2πεL. Here, h is the distance between the tube and the gate (300 nm in our samples); r and L are the tube diameter and length, respectively.
19.
J.
Lefebvre
,
J. F.
Lynch
,
M.
Llaguno
,
M.
Radosavljević
, and
A. T.
Johnson
,
Appl. Phys. Lett.
75
,
3014
(
1999
).
20.
F.
Leonard
and
J.
Tersoff
,
Phys. Rev. Lett.
83
,
5174
(
1999
).
21.
P. L.
McEuen
,
M.
Bockrath
,
D. H.
Cobden
,
Y.
Yoon
, and
S. G.
Louie
,
Phys. Rev. Lett.
83
,
5098
(
1999
).
22.
J.
Liu
,
M. J.
Casavant
,
M.
Cox
,
D. A.
Walters
,
P.
Boul
,
W.
Lu
,
A. J.
Rimberg
,
K. A.
Smith
,
D. T.
Colbert
, and
R. E.
Smalley
,
Chem. Phys. Lett.
303
,
125
(
1999
).
This content is only available via PDF.
You do not currently have access to this content.