1989 Fiscal Year Final Research Report Summary
STUDY OF THE SINGLE ELECTRON TUNNELING EFFECT USING DISCONTINUOUS METAL FILMS
| Project/Area Number |
63550007
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials
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| Research Institution | UNIVERSITY OF TOKYO |
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Principal Investigator |
TAMIYA Sumiko LECTURER, DEPT. OF ELECTRONIC ENGINEERING, UNIVERSITY OF TOKYO, 工学部, 講師 (90010925)
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| Co-Investigator(Kenkyū-buntansha) |
OKABE Yoichi PROFESSOR, DEPT. OF ELECTRONIC ENGINEERING, UNIVERSITY OF TOKYO, 工学部, 教授 (50011169)
OKAMURA Sogo PROFESSOR, TOKYO DENKI UNIVERSITY, 総合研究所, 教授 (50010616)
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| Project Period (FY) |
1988 – 1989
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| Keywords | discontinuous metal film / tunneling junction / liquid He temperature / single electron tunneling effect |
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| Research Abstract |
In a very small Josephson junction, where the junction capacitance is small, its charging energy becomes comparable to the Josephson coupling energy. The charging effect prevents the change of the number of electrons in both sides of the junction.
Recently, a new interesting phenomenon arising from the big charging energy in a small tunneling junction, that is, the single electron tunneling effect is proposed.
The discontinuous metal films are modeled as a network of small tunneling effect using the discontinuous metal films which were composed of series and parallel connections of many metal-insulator- metal contact.
Results are shown as follows. 1. Discontinuous metal films were prepared by the evaporation method in a high vacuum system at the pressure below 2x10^<-5> Pa. Various high-melting-point metals have been used but most of the experiments were done with Pt.
Contact electrodes and the gate electrodes (Cr/Au) were deposited first. For deposition of discontinuous films. substrates were kept in clean and with good thermal contact. Film structure depends critically on substrate preparations and deposition conditions. A typical deposition rate would be 0.03 nm/sec. We deposited Pt of 1.5- 2.0 nm in the average thickness. The size of isolated Pt islands is 5-7 nm in diameter with 1.0-1.5 nm spacings.
The thickness of the films was controlled by a quartz thickness meter and also monitored by the film resistance. Typically, the discontinuous metal films have about 10-100 K OMEGA O. During the deposition, about 1-5 KV/cm electric field was applied in plane to the substrate. 2. The discontinuous metal film was mounted to supporting mount. The mount was dipped into liquid helium. To observed the field effect, the electric field of several KV/cm is applied to the gate electrode of the discontinuous metal film. The field effect was observed for a few films, but was unstable. Unfortunately, the presence of the current quantization was not clear in our experiments.
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Research Products
(2 results)
