High temperature superconductor Josephson junction element and manufacturing method for the same

• US 6,541,789 B1
• Filed: 08/30/1999
• Issued: 04/01/2003
• Est. Priority Date: 09/01/1998
• Status: Expired due to Fees

• Current Assignee: International Superconductivity Technology Center, NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Wen, Jian-Guo, Tanaka, Shoji, Sato, Tetsuro, Koshizuka, Naoki
• Primary Examiner(s): Wilson, Allan R.
• Application Number:
  US09/385,710
• Time in Patent Office: 1,310 Days
• Field of Search: 257/31-33, 257/35
• US Class Current: 257/33
• CPC Class Codes: H10N 60/0941 comprising high-Tc ceramic materials
• CPC Class Codes: H10N 60/124 comprising high-Tc ceramic materials

Abstract

In a method of manufacturing a Josephson junction, a first superconductive layer is formed on a substrate. An insulating film is formed on the first superconductive layer. The insulating film is etched to have an inclination portion. The first superconductive layer is etched using the etched insulating film as a mask, to have an inclination portion. A barrier layer is formed on a surface of the inclination portion of the first superconductive layer. A second superconductive layer is formed on the barrier layer and the inclination portion of the insulating layer.

Claims

1. A Josephson junction comprising:

a first superconductive layer formed on a substrate and having an inclination portion;

an insulating film formed on said first superconductive layer and having an inclination portion following to said inclination portion of said first superconductive layer;

a barrier layer formed on said inclination portion of said first superconductive layer;

a second superconductive layer formed on said inclination portion of said insulating film and said inclination portion of said barrier layer;

wherein said barrier layer has a perovskite structure; and

wherein a material of said barrier layer has a lattice constant from 0.41 nm to 0.43 nm.

2. A Josephson junction according to claim 1, wherein said insulating film contains at least one element selected from the group consisting of La, Sr, Al, Ca and Ta.

7. A Josephson junction according to claim 1, wherein said substrate contains at least one element selected from the group consisting of La, Sr, Al, Ca and Ta.

10. A Josephson junction according to claim 1, wherein said barrier layer is composed of one layer being composed of the material which contains at least one of the elements such as La, Sr, Ca, Al and Ta, and the other layer being formed with at least one of the said elements diffused in the lower superconductive layer.

3. A Josephson junction comprising:

a first superconductive layer formed on a substrate and having an inclination portion;

an insulating film formed on said first superconductive layer and having an inclination portion following to said inclination portion of said first superconductive layer;

a barrier layer formed on said inclination portion of said first superconductive layer;

a second superconductive layer formed on said inclination portion of said insulating film and said inclination portion of said barrier layer; and

wherein a composition of said barrier layer is Y_1-xBa₁Cu_xO_y (x being in a range of 0 to

     1).

4. A Josephson junction according to claim 3, wherein said x is equal to or less than 0.5.

5. A Josephson junction according to claim 4, wherein said x is 0.

8. A Josephson junction according to claim 3, wherein said insulating film contains at least one element selected from the group consisting of La, Sr, Al, Ca and Ta.

9. A Josephson junction according to claim 3, wherein said substrate contains at least one element selected from the group consisting of La, Sr, Al, Ca and Ta.

11. A Josephson junction according to claim 3, wherein said barrier layer is composed of one layer being composed of the material which contains at least one of the elements such as La, Sr, Ca, Al and Ta, and the other layer being formed with at least one of the said elements diffused in the lower superconductive layer.

6. A Josephson junction device comprising:

a first superconductive layer formed on a substrate;

2 or more interlayer insulating films provided on said first superconductive layer apart from each other; and

2 or more second superconductive layers respectively formed on said interlayer insulating layers;

wherein each of said interlayer insulating films has a film thickness equal to or less than 2 nm.; and

said first superconductive layer and said second superconductive layer are YBaCuO superconductive layers.