Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is
Reexamination Certificate
2000-09-26
2002-05-14
Crane, Sara (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
C257S030000, C257S031000, C257S033000, C438S400000, C438S416000, C505S329000, C505S702000
Reexamination Certificate
active
06388268
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to semiconducting yttrium-barium-copper-oxygen (YBCO) device in which semiconducting YBCO film is locally converted to a nonconducting YBCO film using a conductive atomic force microscope (AFM) and superconducting YBCO device in which superconducting YBCO film is locally converted to a nonsuperconducting YBCO film by an AFM, and manufacturing methods therefor.
2. Description of the Related Art
FIG. 1
is a graph showing the electrical characteristic of a typical semiconducting YBCO film, and
FIG. 2
is a graph showing the electrical characteristic of a typical superconducting YBCO film. It can be seen that as the temperature falls, a semiconducting YBCO film shows a high resistivity, while a superconducting YBCO film shows superconducting properties, i.e., the resistivity drops to zero below a specific critical temperature. There are various factors that determine the semiconducting properties or superconductivity of YBCO films. As one of these factors,
FIG. 3
shows experimental results, which indicate that the semiconducting and superconducting properties are dependent on oxygen content. More specifically,
FIG. 3
shows the electrical properties with respect to changes in the value of parameter y where y=7−x in YBa
2
Cu
3
O
7−x
film. According to the experimental results shown in
FIG. 3
, a YBCO film shows semiconducting properties if y≦6.3 while it shows superconducting properties if y≧6.5. The YBCO material has difficulty in manufacturing tunnel junctions through dry or chemical etching due to its chemical sensitivity. Furthermore, it is well known that the material has a problem in high volume production since the characteristics between thus manufactured tunnel junctions are irregular. Accordingly, adoption of a planar patterning method which locally converts YBCO film through electrical or physical change is required.
SUMMARY OF THE INVENTION
To solve the above problem, it is a first objective of the present invention to provide a semiconducting yttrium-barium-copper-oxygen (YBCO) device which is locally converted by an atomic force microscope (AFM) in such a way as to electrically convert a portion of YBCO film, and a manufacturing method thereof.
It is a second objective to provide a superconducting YBCO device which is locally converted by an AFM in such a way as to electrically convert a portion of YBCO film, and a manufacturing method thereof.
Accordingly, to achieve the first objective, the present invention provides a semiconducting YBCO device locally converted by AFM which includes a MgO substrate, a semiconducting YBCO film stacked on the MgO substrate, a nonconducting YBCO region locally converted so as to form a tunnel junction in the semiconducting YBCO film, and electrodes which are formed at the ends of the semiconducting YBCO film.
The present invention also provides a method of manufacturing a semiconducting YBCO device locally converted by an AFM including the steps of: depositing a semiconducting YBCO film over a MgO substrate; forming electrodes at the ends of the semiconducting YBCO film, and placing an AFM tip on the semiconducting YBCO film between the electrodes and applying a predetermined voltage between the AFM tip and the electrodes to convert a local region of the semiconducting YBCO film contacted by the AFM tip to a nonconducting YBCO so that a tunnel junction may be formed in the local region of the semiconducting YBCO film.
To achieve the second objective, the present invention provides a superconducting YBCO device locally converted by an AFM including a MgO substrate, a superconducting YBCO film stacked on the MgO substrate, a nonsuperconducting YBCO region locally converted so as to form a tunnel junction in the superconducting YBCO film, and electrodes which are formed at the ends of the superconducting YBCO film.
The present invention provides a method of manufacturing a superconducting YBCO device locally converted by an AFM including the steps of: depositing a superconducting YBCO film over a MgO substrate; forming electrodes at the ends of the superconducting YBCO film; and placing an AFM tip on the superconducting YBCO film between the electrodes and applying a predetermined voltage between the AFM tip and the electrodes to convert a local region of the superconducting YBCO film contacted by the AFM tip to a nonsuperconducting YBCO so that a tunnel junction may be formed in the local region of the superconducting YBCO film.
REFERENCES:
patent: 5763933 (1998-06-01), White
patent: 6147360 (2000-11-01), Odagawa et al.
patent: 6160266 (2000-12-01), Odagawa et al.
patent: 6207067 (2001-03-01), Yutani et al.
Kim Byong-man
Song In-sang
Burns Doane Swecker & Mathis L.L.P.
Crane Sara
Samsung Electronics Co,. Ltd.
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