| 摘要 |
PURPOSE:To remarkably reduce the area of a junction and to obtain an element adapted for a high speed switching by forming the weak coupler of a Josephson- junction device of a superconductor oxidized in crystal grain boundary, a normal conductor or a semiconductor. CONSTITUTION:When the crystal grain boundary of the weak coupler 5 of a quasi-flat surface type Josephson-junction device 1 is oxidized, it is operated as a tunnel junction. Then, a weak coupler 5 is formed over upper and lower electrodes across upper and lower sections 2, 3 electrodes of a superconductor formed through an insulating layer, and the side of an insulating layer 4 to form a superconductor oxidized in crystal grain boundary by anodic oxidation, a normal conductor, a semimetal or a semiconductor at the weak coupler. Since a tunnel type Josephson-junction device is determined by the width (c) and the thickness (t) of the coupler in the area of the junction to be extremely reduced, a current density can be increased, an electrostatic capacity can be reduced to obtain an element adapted for a high speed switching, and a critical current value can be easily set and controlled.
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