JPH02154484A - Josephson element - Google Patents
Josephson elementInfo
- Publication number
- JPH02154484A JPH02154484A JP63309321A JP30932188A JPH02154484A JP H02154484 A JPH02154484 A JP H02154484A JP 63309321 A JP63309321 A JP 63309321A JP 30932188 A JP30932188 A JP 30932188A JP H02154484 A JPH02154484 A JP H02154484A
- Authority
- JP
- Japan
- Prior art keywords
- film
- substrate
- grain boundary
- josephson
- granular
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000758 substrate Substances 0.000 claims abstract description 21
- 239000002887 superconductor Substances 0.000 claims abstract description 14
- 239000013078 crystal Substances 0.000 claims abstract description 9
- 230000004907 flux Effects 0.000 abstract description 5
- 230000003071 parasitic effect Effects 0.000 abstract description 2
- 239000010408 film Substances 0.000 description 23
- 230000000694 effects Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 230000005668 Josephson effect Effects 0.000 description 1
- 229910002370 SrTiO3 Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000002048 anodisation reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、酸化物超伝導体を電極に使用したジョセフソ
ン接合の構造に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a Josephson junction structure using an oxide superconductor as an electrode.
（従来の技術）
Ｙ−Ｂａ−Ｃｕ−０，Ｂ１−８ｒ−Ｃａ−Ｃｕ−０，Ｔ
ｌ−Ｂａ−Ｃａ−Ｃｕ−０などの高温酸化物超伝導体の
粒界にはジョセフソン接合が出来やすい事がわかってい
る。このような粒界接合を利用した、粒状薄膜からなる
ジョセフソン素子の模式図を第３図（ａＸｂ）に示した
。第３図中１１は非エピタギシャル基板、つまりエピタ
キシャル膜が出来ない基板であり、２１は粒状に成長し
た高温超伝導体膜、３はリソグラフィ技術で形成したく
びれ部で、４は粒界に出来ているジョセフソン接合、５
はパッド部である。３のようなくびれな部が作られてい
るので、この部分の接合の電流密度が他の部分の電流密
度よりも大きくなり、大きな超伝導位相差が表われるの
で、この部分でのジョセフソン効果が強調されるように
なっている。(Prior art) Y-Ba-Cu-0,B1-8r-Ca-Cu-0,T
It is known that Josephson junctions are likely to form at the grain boundaries of high-temperature oxide superconductors such as l-Ba-Ca-Cu-0. A schematic diagram of a Josephson element made of a granular thin film utilizing such grain boundary bonding is shown in FIG. 3 (aXb). In Fig. 3, 11 is a non-epitaxial substrate, that is, a substrate on which an epitaxial film cannot be formed, 21 is a high-temperature superconductor film grown in grains, 3 is a constriction formed by lithography technology, and 4 is a constriction formed at grain boundaries. Josephson junction, 5
is the pad part. Since a constricted part as shown in 3 is created, the current density of the junction in this part becomes larger than the current density in other parts, and a large superconducting phase difference appears, so the Josephson effect in this part is becoming emphasized.
（発明が解決しようとする課題）
このような従来のジョセフソン素子はくびれ部のみでは
なくパッド部にも無数の粒界ジョセフソン接合が出来て
いる。ジョセフソン接合のアレイが出来ている事により
、パッド部による余計な量子干渉効果が表われる事が知
られている。また磁束は粒界にそって比較的自由に運動
出来るので、パッド間に大きな電圧・雑音が表われる事
もわかってる。さらにこのような余計な磁束が粒界にそ
って膜内に入りこむ事により、効果的に磁束侵入長が大
幅に増加するので、パッド部のカイナティノクインダク
タンスが実際に増加する事が知られている。このような
インダクタンスの増加は５ＱＵＩＤの設計、回路設計な
どに大きな悪影響をおよぼす。(Problems to be Solved by the Invention) In such a conventional Josephson element, numerous grain boundary Josephson junctions are formed not only in the constriction portion but also in the pad portion. It is known that due to the formation of an array of Josephson junctions, unnecessary quantum interference effects appear due to the pad portion. It is also known that because the magnetic flux can move relatively freely along the grain boundaries, large voltages and noise appear between the pads. Furthermore, it is known that when such extra magnetic flux enters the film along the grain boundaries, the magnetic flux penetration length effectively increases significantly, and the kainatino inductance of the pad area actually increases. There is. Such an increase in inductance has a large adverse effect on 5QUID design, circuit design, and the like.
（課題を解決するための手段）
前述の問題点を解決するために本発明が提供する手段は
、基板上にエピタキシャル成膜されている高温酸化物超
伝導体膜において、前記基板上に結晶ダメージ部有し、
前記結晶ダメージ部上のみに粒状の高温酸化物超伝導体
膜が出来ており、その粒界にジョセフソン接合を含んで
いるジョセフソン素子を提供する事である。(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides means for solving the above-mentioned problems in a high temperature oxide superconductor film that is epitaxially formed on a substrate. have,
It is an object of the present invention to provide a Josephson element in which a granular high-temperature oxide superconductor film is formed only on the damaged crystal part, and a Josephson junction is included in the grain boundaries.
（作用）
本発明はパッド部を単結晶膜に近いエピタキシャル膜で
構成し、くびれ部のみ粒状膜を使うものである。このよ
うにするとパッド部での磁束の運動がおさえられ、余計
な電圧・雑音、インダクタンスなどを取りのぞく事が出
来る。第２図（ａＸｂ）は本発明の詳細な説明するもの
である。第２図中にはエピタキシャル成膜が出来る基板
、１５は基板上の結晶にダメージがある部分、２１は粒
状の高温超伝導体膜、２２はエピタキシャル成膜された
高温超伝導体膜、４は粒界である。第２図（ａ）は基板
」二にエピタキシャル成膜された高温超伝導膜の断面模
式図である。エピタキシャル膜においては粒界が成長し
にくいので、ジョセフソン結合している部分がほとんど
ない。第２図（ｂ）では部分的に粒界ジョセフソン結合
を作るために、あらかじめ基板」二の限られた部分に基
板の結晶にダメージを入れた各所を作っておく。そうす
るとその部分の結晶性が失なわれるので、その上にはエ
ピタキシャル成膜はされず、粒状の高温超伝導体膜が出
来る。このようにして限られた所にのみ粒界ジョセフソ
ン接合を限定して作る事が出来、パッドの部分をエピタ
キシャル膜でおきかえる事が出来る。(Function) In the present invention, the pad portion is formed of an epitaxial film similar to a single crystal film, and a granular film is used only in the constriction portion. In this way, the movement of magnetic flux in the pad section is suppressed, and unnecessary voltage, noise, inductance, etc. can be removed. Figure 2 (aXb) provides a detailed explanation of the invention. In Fig. 2, there is shown a substrate on which epitaxial film formation can be performed, 15 is a damaged part of the crystal on the substrate, 21 is a granular high-temperature superconductor film, 22 is an epitaxially formed high-temperature superconductor film, and 4 is a grain boundary. It is. FIG. 2(a) is a schematic cross-sectional view of a high temperature superconducting film epitaxially formed on a substrate. In an epitaxial film, since grain boundaries are difficult to grow, there are almost no Josephson bonded parts. In FIG. 2(b), in order to partially create grain boundary Josephson bonds, the crystals of the substrate are damaged at various locations in limited areas of the substrate. In this case, the crystallinity of that part is lost, so no epitaxial film is formed on it, and a granular high-temperature superconductor film is formed. In this way, a grain boundary Josephson junction can be formed only in a limited area, and the pad portion can be replaced with an epitaxial film.
（実施例）
第１図に本発明の実施例の」二面図を示す。本図中１３
は５ｒＴｉｏ３基板、２３はエビタギシＡ・ル成膜され
たＹＢａ２Ｃｕ３０７−８膜、２４は粒状のＹＢａ２Ｃ
ｕ３０７−８．１５はＳｒＴｉＯ３上のイオンダメージ
を加えられた部分、５はパッド部である。５ｒＴｉ○３
基板１３上には約７５０’Ｃ以上でＹＢａ２Ｃｕ３０７
−ｌ、がエピタキシャル成膜出来る。この５ｒＴｉ○３
基板上にあらかじめイオンビームで結晶ダメージ部を作
っておくと、その上のＹＢａ２Ｃｕ３０７６が粒状に成
膜され、粒界ジョセフソン接合が出来る。リングラフィ
技術でＹＢａ２Ｃｕ３０７−８膜を粒状の部分を介した
二端子にパターニングすると、パント部に粒界ジョセフ
ソン接合がない高温ジョセフソン素子が出来る。(Embodiment) FIG. 1 shows a two-sided view of an embodiment of the present invention. 13 in this figure
5rTio3 substrate, 23 is YBa2Cu307-8 film formed by Evitagishi A. Le, 24 is granular YBa2C
u307-8.15 is the ion-damaged portion on SrTiO3, and 5 is the pad portion. 5rTi○3
YBa2Cu307 on the substrate 13 at about 750'C or higher
-l can be epitaxially formed. This 5rTi○3
If a crystal damaged area is previously created on the substrate using an ion beam, YBa2Cu3076 is deposited in grains on the damaged area, creating a grain-boundary Josephson junction. When a YBa2Cu307-8 film is patterned into two terminals via a granular portion using a phosphorography technique, a high-temperature Josephson device without grain boundary Josephson junctions in the punt portion can be obtained.
本実施例以外にもＭｇＯ基板、５ｒＴｉｏ３基板上のＢ
ａＰｂ１−ｘＢｉｘＯ３膜、Ｍｇ○基板上のＢ１２５ｒ
２ＣａＣｕ２０Ｘ及びＢ１２５ｒ２Ｃａ２Ｃｕａ○８な
ども当然者えらる。In addition to this example, B on MgO substrate, 5rTio3 substrate
aPb1-xBixO3 film, B125r on Mg○ substrate
2CaCu20X and B125r2Ca2Cua○8 are also natural choices.
また基板ダメージもイオンビームによるだけでなく、プ
ラズマダメージ、陽極化などの種々の通常手段が考えら
れる。Further, damage to the substrate is not limited to ion beam damage, but various conventional methods such as plasma damage and anodization can be considered.
（発明の効果）
以」二説明したように、本発明を使用する事により、電
圧・雑音、寄生インダクタンスなどが発生しにくいエピ
タキシャル膜を主体とした粒界ジョセフソン素子が得ら
れる。(Effects of the Invention) As explained below, by using the present invention, a grain boundary Josephson element mainly composed of an epitaxial film in which voltage, noise, parasitic inductance, etc. are less likely to occur can be obtained.
第１図は本発明の実施例の平面図、第２図（ａＸｂ）は
本発明の詳細な説明した断面図、第３図（ａＸｂ）はそ
れぞれ従来例を説明した平面図と断面図。
１１、非エピタキシャル基板
１２、エビタギシャル基板
１３、 ８ｒＴｉ０３基板
１４、基板上のダメージ部
１５、イオンダメージ部
２１、粒状高温超伝導体膜
２２、エピタキシャル高温超伝導体膜
２３、エピタキシャルＹＢａ２Ｃｕ３Ｏ７５膜２４、粒
状ＹＢａ２Ｃｕ３０７−８膜
３、くびれ部
４、粒界接合
５、パッド部FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 (aXb) is a cross-sectional view explaining the present invention in detail, and FIG. 3 (aXb) is a plan view and a cross-sectional view of a conventional example, respectively. 11, non-epitaxial substrate 12, epitaxial substrate 13, 8rTi03 substrate 14, damaged part 15 on substrate, ion damaged part 21, granular high temperature superconductor film 22, epitaxial high temperature superconductor film 23, epitaxial YBa2Cu3O75 film 24, granular YBa2Cu307 -8 Membrane 3, constriction 4, grain boundary junction 5, pad part
Claims (1)
導体エピタキシャル膜が設けられ前記結晶ダメージ部上
のみに粒状の高温酸化物超伝導体膜が出来ており、その
粒界にジョセフソン接合を含んでいるジョセフソン素子
。A high-temperature oxide superconductor epitaxial film is provided on a substrate that partially has a crystal damaged area, and a granular high-temperature oxide superconductor film is formed only on the crystal damaged area, and Josephson junctions are formed at the grain boundaries. Josephson element containing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63309321A JPH02154484A (en) | 1988-12-06 | 1988-12-06 | Josephson element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63309321A JPH02154484A (en) | 1988-12-06 | 1988-12-06 | Josephson element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02154484A true JPH02154484A (en) | 1990-06-13 |
Family
ID=17991609
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63309321A Pending JPH02154484A (en) | 1988-12-06 | 1988-12-06 | Josephson element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02154484A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02253670A (en) * | 1989-03-27 | 1990-10-12 | Shimadzu Corp | Grain boundary josephson junction device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0195576A (en) * | 1987-10-07 | 1989-04-13 | Matsushita Electric Ind Co Ltd | Manufacture of thin-film superconducting device |
-
1988
- 1988-12-06 JP JP63309321A patent/JPH02154484A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0195576A (en) * | 1987-10-07 | 1989-04-13 | Matsushita Electric Ind Co Ltd | Manufacture of thin-film superconducting device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02253670A (en) * | 1989-03-27 | 1990-10-12 | Shimadzu Corp | Grain boundary josephson junction device |
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