1997 Fiscal Year Final Research Report Summary
Fabrication of High-Tc Superconducting Co-planar Josephson Junctions Using Focused Ion Beam
| Project/Area Number |
07455147
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OKABE Yoichi The University of Tokyo, RCAST,Professor, 先端科学技術研究センター, 教授 (50011169)
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| Co-Investigator(Kenkyū-buntansha) |
KITAGAWA Manabu The University of Tokyo, RCAST,Research Associate, 先端科学技術研究センター, 助手 (30110711)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Focused Ion Beam / Co-planar / YBaCuO / 高温超伝導 |
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| Research Abstract |
YBaCuOco-planar junctions were fabricated using Focused Ion Beam (FIB) . A YBaCuO has two-dimentional conductivity of super-current. The co-planar junction has the most effective current flow in the YBaCuO Junctions. We have been fabricated two types of the co-planar junctions using FIB (One is the colally damaged substrate type. The other is the locally ion irradiate type) .
YBaCuO co-planar Josephson junctions with the abnormally grown YBaCuO were produed using Focused Ion Beam. FIB was used to form a narrow region of ion damage on the MgO (100) substrate.
The junctions were fabricated by changing the thickness of a YBaCuO thin film. The junctions had the thickness dependence of the characterstics. From the observation of the junction surface, the junction length was decreased with increasing film thickness by the horizontal growth of the normally grown YBaCuO in the thinner film junctions. It is considered that the Jeosephson current for the thicker film junctions flows dominantly in the microshorts, and Josephson current for the thinner film junctions flows in the abnormally grown YBaCuO area.
Josephson junctions were fabricated by irradiating Be ions on a YBaCuO thin film with FIB.The junctions had the I-V curve of RSJ,the IcRn product from 0.6mV to 2.0mV,and a good magnetic response at 4.2K.The critical current density of the junctions decreased exponentially with increasing the ion fluence. From the estimation of the damage distrubution, the junction length increased with the ion fluence. The damaged YBaCuO thin film showed the characteristic of the normal metal. Therefore, it is considered that the junctions had the SNS type junction with a proximity effect. When the junctions which were fabricated six mounth ago were measured, the current distribution of the junction did not changed. The junction stability was good.
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