Jpn. J. Appl. Phys. 42 (2003) pp. 4743-4747 |Next Article| |Table of Contents|
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Observation of Coulomb Blockade and Interference Using a Carbon Nanotube Tip
National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan
1Department of Electronics, Yamanashi University, 4-3-1 Takeda, Kofu 400-8511, Japan
(Received October 31, 2002; accepted for publication February 21, 2003)
Using a carbon nanotube (CNT) bundle tip as a field emitter, we have observed both Coulomb blockade and interference fringes in consecutive measurements. When Coulomb blockade is observed, decoherence of the electron wave occurs. This was observed using a double-tunnel junction consisting of a CNT tip and a CNT sample. When the CNT sample was projected onto a screen by an electron wave from the CNT tip, interference fringes were observed. This shows that the electron is first observed at the central electrode as a Coulomb blockade, next it is observed at the CNT sample as current when the electron leaves from the central electrode (the CNT tip) and finally observed as fringes passing through the CNT sample. These results show that the system's wave function cannot be written as a direct product of independent substates.
- K. Fujikawa and Y. A. Ono: Quantum Coherence and Decoherence (Elsevier, Amsterdam, 1996).
- J.-W. Pan, D. Bouwmeester, M. Daniell, H. Weinfurther and A. Zeilinger:
Nature 403 (2000) 515[CrossRef].
- C. A. Sakett, D. Kielpinski, B. E. King, C. Langer, V. Meyer, C. J. Myatt, M. Rowe, Q. A. Turchette, W. M. Itano, D. J. Wineland and C. Monroe:
Nature 404 (2000) 256[CrossRef].
- A. M. Air, A. Vaziri, G. Weihs and A. Zeilingr:
Nature 412 (2001) 313[CrossRef].
- L. Davidovich, A. Maali, M. Brune, J. M. Raimond and S. Haroche:
Phys. Rev. Lett. 71 (1993) 2360[APS].
- M. Brune, E. Hagley, J. Dreyer, X. Maître, A. Maali, C. Wunderlich, J. M. Raimond and S. Haroche:
Phys. Rev. Lett. 77 (1996) 4887[APS].
- E. Hagley, X. Maitre, G. Nogues, C. Wunderlich, M. Brune, J. M. Raimond and S. Haroche:
Phys. Rev. Lett. 79 (1997) 1[APS].
- G. Falci, R. Fazio, G. M. Palma, J. Siewert and V. Vedral:
Nature 407 (2000) 355[CrossRef].
- Y. Yamamoto, G. Bjork, H. Heimann and R. Horowicz: Optics of Semiconductor Nanostructures, eds. F. Henneberger, S. Schmitt-Rink and E. O. Gobel (Academie Verlag, Berlin, 1993) p. 547.
- Vu T. Binh and V. Semet: Ultramicroscopy 73 (1998) 107.
- H.-W. Fink and C. Shonenberger:
Nature 398 (1999) 407[CrossRef].
- J. Spence, W. Qian and X. Zhang: Ultramicroscopy 55 (1994) 19.
- H. Park, J. Park, A. K. L. Lim, E. H. Anderson, A. P. Alivisatos and P. L. McEuen:
Nature 407 (2000) 57[CrossRef].
- H. Hori: Optical and Electronic Process of Nano-matters, ed. M. Ohtsu (Kluwer Academic Publishers, Dordrecht, 2001) p. 1.
- W. Liang, M. Bockrath, D. Bozovic, J. H. Hafner, M. Tinkham and H. Park:
Nature 411 (2001) 665[CrossRef].
- T. W. Tombler, C. Zhou, L. Alexseyev, J. Kong, H. Dai, L. Liu, C. S. Jayanthi, M. Tang and S.-Y. Wu:
Nature 405 (2000) 769[CrossRef].
- S. Sanvito, Y.-Y. Kwon, D. Tomanek and C. J. Lambert:
Phys. Rev. Lett. 84 (2000) 1974[APS].
- All experiments were performed in ultra high vacuum (UHV) at room temperature. A 5-nm-diameter bundle of CNT [rf21] was dissolved in difluoroethane and a droplet was placed on a Ni microgrid. After the solvent evaporated, the CNT sample was placed into a UHV chamber.
- The Fresnel projection microscope consists of a sharp field emission tip which can be moved in x, y and z directions, a freestanding sample and an MCP aligned perpendicular to the tip apex. About 100 V negative voltage is applied to the tip to produce electron field emission from the tip. The field emission electron beam has a spherical shape and originates from a single point: the tip apex. If a freestanding object is placed in the beam, a magnified shadow image of the object is formed on the MCP. Moving the tip in the z direction allows changing the magnification by the order of 106.
- This CNT attachment to the W tip was further confirmed by comparing the field emission images from the W tip and the W tip with CNT. Since cold-milled polycrystalline wire was used as a tip, the tip apex shows a (110) facet. [rf23] The (110) facet shows fourfolded symmetry and a fourfolded symmetry field emission image was obtained (data not shown). Compared to the field emission image from the W tip, the CNT attached tip shows less symmetrical field emission images.
- CarboLex Inc. USA.
- R. Gomer: Field Emission and Field Ion Microscopy (Harvard University Press, 1961).
- The latter reason is self suggestive due to the following I-V characteristics: The closer the W tip approaches the CNT sample, the larger the current flowing from the tip to the sample. The nonlinear behavior is governed mainly by the contact behavior between the W tip and CNT. The contact resistance varies from 100 kΩ to 100 MΩ by our measurements. When a CNT is attached to the W tip apex, the contact resistance between the W tip and the CNT is also thought to fall in this range. As the resistance is larger than the quantum resistance, a Coulomb blockade is observed.
- Field emission current increases with the bias voltage so that each step height of the Coulomb staircase increases with the bias voltage. This is the reason the di/dv value increases with the bias voltage.
- The CNT-tip and the CNT sample distance d ratio is calculated from 1, 1.08, 1.18, 1.45 for the onset voltage V from 65, 70, 77, 94 V by the condition that the electric field (V/d) is constant.
- H. Imamura, J. Chiba, S. Mitani, K. Takanashi, S. Takahashi, S. Maekawa and H. Fujimori:
Phys. Rev. B 61 (2000) 46[APS].