JPH05291632A - Superconductive junction structure - Google Patents
Superconductive junction structureInfo
- Publication number
- JPH05291632A JPH05291632A JP4118014A JP11801492A JPH05291632A JP H05291632 A JPH05291632 A JP H05291632A JP 4118014 A JP4118014 A JP 4118014A JP 11801492 A JP11801492 A JP 11801492A JP H05291632 A JPH05291632 A JP H05291632A
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- JP
- Japan
- Prior art keywords
- superconducting
- superconductive
- oxide
- junction structure
- thin film
- 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.)
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- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、超電導接合構造体に関
する。より詳細には、酸化物超電導体を用いており、作
製が容易である新規な超電導接合構造体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting junction structure. More specifically, the present invention relates to a novel superconducting junction structure that uses an oxide superconductor and is easy to manufacture.
【０００２】[0002]
【従来の技術】ジョセフソン接合に代表される超電導接
合を実現する構成は各種あって、最も好ましい構造は、
一対の超電導体で薄い非超電導体をはさんだトンネル型
の接合である。しかしながら、点接触型、マイクロブリ
ッジ型等一対の超電導体を弱く結合した超電導接合も、
特性は異なるもののジョセフソン効果を発揮する。一般
に、このような超電導接合を実現する超電導接合構造体
は非常に微細な構造であり、上記の超電導体および非超
電導体は、いわゆる薄膜で構成されている。2. Description of the Related Art There are various configurations for realizing a superconducting junction represented by Josephson junction, and the most preferable structure is
It is a tunnel-type junction that sandwiches a thin non-superconductor with a pair of superconductors. However, superconducting junctions that weakly couple a pair of superconductors such as point contact type and micro bridge type
Although it has different characteristics, it exerts the Josephson effect. Generally, a superconducting junction structure that realizes such a superconducting junction has a very fine structure, and the above-mentioned superconductor and non-superconductor are composed of so-called thin films.
【０００３】例えば、超電導体に酸化物超電導体を使用
してトンネル型超電導接合構造体を実現する場合には、
基板上に第１の酸化物超電導薄膜、非超電導体薄膜およ
び第２の酸化物超電導薄膜を順に積層する。For example, when an oxide superconductor is used as the superconductor to realize a tunnel type superconducting junction structure,
A first oxide superconducting thin film, a non-superconductor thin film, and a second oxide superconducting thin film are sequentially laminated on a substrate.
【０００４】非超電導体には、用途により例えばMgＯ等
の絶縁体、Si等の半導体、Au等の金属が使用され、それ
ぞれ異なる特性の超電導接合を構成する。Depending on the application, an insulator such as MgO, a semiconductor such as Si, or a metal such as Au is used for the non-superconductor, and each constitutes a superconducting junction having different characteristics.
【０００５】トンネル型超電導接合構造体における非超
電導体の厚さは、超電導体のコヒーレンス長によって決
まる。酸化物超電導体は、コヒーレンス長が非常に短い
ため、酸化物超電導体を使用したトンネル型超電導接合
構造体においては、非超電導体の厚さは数nm程度にしな
ければならない。The thickness of the non-superconductor in the tunnel-type superconducting junction structure is determined by the coherence length of the superconductor. Since the oxide superconductor has a very short coherence length, the thickness of the non-superconductor must be about several nm in the tunnel-type superconducting junction structure using the oxide superconductor.
【０００６】また、点接触型超電導接合構造体、マイク
ロブリッジ型超電導接合構造体は、いずれも一対の超電
導体の弱結合が実現するような非常に微細な加工を必要
とする。一方、超電導接合の動作特性を考慮すると、超
電導接合構造体を構成する各層の結晶性がよく、単結晶
または単結晶にごく近い配向性を有する多結晶でなけれ
ばならない。Further, both the point-contact type superconducting junction structure and the microbridge type superconducting junction structure require very fine processing for realizing weak coupling of a pair of superconductors. On the other hand, considering the operating characteristics of the superconducting junction, each layer constituting the superconducting junction structure must have good crystallinity and be a single crystal or a polycrystal having an orientation very close to that of a single crystal.
【０００７】[0007]
【発明が解決しようとする課題】上記のトンネル型超電
導接合構造体を酸化物超電導体を使用して実現する場合
には、それぞれ結晶性のよい第１の酸化物超電導薄膜、
非超電導体の薄膜および第２の酸化物超電導薄膜を積層
しなければならない。酸化物超電導薄膜上にごく薄く、
且つ結晶性のよい非超電導体の薄膜を積層することは困
難であり、この非超電導体薄膜のさらに上に結晶性のよ
い酸化物超電導薄膜を形成するのは酸化物超電導体の特
性上非常に困難である。また、上記の積層構造が実現し
ても、従来は酸化物超電導体と非超電導体との界面の状
態が良好でなく、安定して所望の特性が得られなかっ
た。When the above tunnel-type superconducting junction structure is realized by using an oxide superconductor, the first oxide superconducting thin film having good crystallinity,
A non-superconductor thin film and a second oxide superconducting thin film must be laminated. Very thin on oxide superconducting thin film,
It is difficult to stack a thin film of a non-superconductor having good crystallinity, and it is very difficult to form an oxide superconducting thin film of good crystallinity on top of this non-superconductor thin film because of the characteristics of the oxide superconductor. Have difficulty. Further, even if the above-mentioned laminated structure is realized, conventionally, the state of the interface between the oxide superconductor and the non-superconductor was not good, and desired characteristics could not be stably obtained.
【０００８】一方、点接触型超電導接合構造体、マイク
ロブリッジ型超電導接合構造体を実現するような、微細
な加工を酸化物超電導薄膜に施すことも非常に困難であ
り、安定した性能の超電導接合構造体を再現性よく作製
することができなかった。On the other hand, it is very difficult to perform minute processing on the oxide superconducting thin film so as to realize a point contact type superconducting junction structure or a microbridge type superconducting junction structure, and a superconducting junction having a stable performance. The structure could not be produced with good reproducibility.
【０００９】そこで、本発明の目的は、上記従来技術の
問題点を解決した、酸化物超電導体を用いた新規な構成
の超電導接合構造体を提供することにある。Therefore, an object of the present invention is to provide a superconducting junction structure having a novel structure using an oxide superconductor, which solves the above problems of the prior art.
【００１０】[0010]
【課題を解決するための手段】本発明に従うと、第１お
よび第２の超電導領域を、結合部に障壁が発生するよう
弱く結合させて構成される弱結合型超電導接合を実現し
ている構造体において、前記第１および第２の超電導領
域が、一体のｃ軸が膜面に平行な酸化物超電導薄膜で形
成され、前記障壁が前記酸化物超電導薄膜を構成する酸
化物超電導体結晶のCu−Ｏ面間の結晶面であることを特
徴とする超電導接合構造体が提供される。According to the present invention, a structure realizing a weak-coupling type superconducting junction constituted by weakly connecting first and second superconducting regions so that a barrier is generated at a connecting portion. In the body, the first and second superconducting regions are formed of an oxide superconducting thin film whose integral c-axis is parallel to the film surface, and the barrier is Cu of an oxide superconducting crystal forming the oxide superconducting thin film. Provided is a superconducting junction structure characterized by being a crystal plane between -O planes.
【００１１】[0011]
【作用】本発明の超電導接合構造体は、第１および第２
の超電導領域が一体の酸化物超電導薄膜で構成されてお
り、障壁がこの酸化物超電導薄膜を構成する酸化物超電
導体結晶のCu−Ｏ面間の結晶面になっている。従って、
障壁が非常にシャープであり、超電導接合としての特性
が優れている。The superconducting junction structure of the present invention has the first and second superconducting structures.
Of the superconducting region is composed of an integrated oxide superconducting thin film, and the barrier is the crystal plane between the Cu-O planes of the oxide superconducting crystals constituting the oxide superconducting thin film. Therefore,
The barrier is very sharp and has excellent characteristics as a superconducting junction.
【００１２】本発明の超電導接合構造体に使用する酸化
物超電導体としては、Ｙ1Ba2Cu3Ｏ7-X、Bi2Sr2Ca2Cu3Ｏ
x 、Tl2Ba2Ca2Cu3Ｏx 等が使用できるが、特にBi2Sr2Ca
2Cu3Ｏx が好ましい。これらの酸化物超電導体は、結晶
構造が層状ペロブスカイトと呼ばれる多層構造になって
おり、通常この多層構造の内のCu−Ｏ面を超電導電流が
流れる。逆に、Cu−Ｏ面に垂直な方向には超電導電流が
流れ難く、この方向の臨界電流密度は小さくなってい
る。従って、Cu−Ｏ面に垂直に大きな超電導電流が流れ
るようにすると、Cu−Ｏ面間の結晶面が障壁となって、
超電導接合が成立する。従って、本発明の超電導接合構
造体は、障壁が非常にシャープであり、超電導接合とし
ての特性が優れている。また、Bi2Sr2Ca2Cu3Ｏx および
Bi2Sr2Ca1Cu2Ｏx はCu−Ｏ面間の結合が弱いので特に好
ましい。The oxide superconductor used in the superconducting junction structure of the present invention includes Y 1 Ba 2 Cu 3 O 7-X , Bi 2 Sr 2 Ca 2 Cu 3 O.
x , Tl 2 Ba 2 Ca 2 Cu 3 O x, etc. can be used, but especially Bi 2 Sr 2 Ca
2 Cu 3 O x is preferred. The crystal structure of these oxide superconductors is a multilayer structure called a layered perovskite, and the superconducting current usually flows through the Cu-O plane of this multilayer structure. On the contrary, it is difficult for the superconducting current to flow in the direction perpendicular to the Cu-O plane, and the critical current density in this direction is small. Therefore, when a large superconducting current flows perpendicularly to the Cu-O plane, the crystal plane between the Cu-O planes becomes a barrier,
Superconducting junction is established. Therefore, the superconducting junction structure of the present invention has a very sharp barrier and has excellent characteristics as a superconducting junction. In addition, Bi 2 Sr 2 Ca 2 Cu 3 O x and
Bi 2 Sr 2 Ca 1 Cu 2 O x is particularly preferable because the bond between the Cu and O faces is weak.
【００１３】以下、本発明を実施例によりさらに詳しく
説明するが、以下の開示は本発明の単なる実施例に過ぎ
ず、本発明の技術的範囲をなんら制限するものではな
い。Hereinafter, the present invention will be described in more detail with reference to examples, but the following disclosure is merely examples of the present invention and does not limit the technical scope of the present invention.
【００１４】[0014]
【実施例】図１に、本発明の超電導接合構造体の一例を
示す。図１は本発明の超電導接合構造体の平面図であ
り、本発明の超電導接合構造体は、基板５上に形成され
たａ軸配向の酸化物超電導薄膜でそれぞれ構成された第
１の超電導領域１、第２の超電導領域２および結合部３
を備える。超電導領域１、２および結合部３を構成する
酸化物超電導薄膜のCu−Ｏ面は、図面の上下方向に平行
に並んでおり、超電導領域１および２間を流れる超電導
電流の方向は、特に結合部３では、Cu−Ｏ面に対して垂
直である。EXAMPLE FIG. 1 shows an example of a superconducting junction structure of the present invention. FIG. 1 is a plan view of a superconducting junction structure of the present invention. The superconducting junction structure of the present invention includes a first superconducting region formed of an a-axis oriented oxide superconducting thin film formed on a substrate 5. 1. Second superconducting region 2 and joint 3
Equipped with. The Cu-O planes of the oxide superconducting thin films forming the superconducting regions 1 and 2 and the joint portion 3 are arranged in parallel in the vertical direction of the drawing, and the direction of the superconducting current flowing between the superconducting regions 1 and 2 is particularly large. In part 3, it is perpendicular to the Cu-O plane.
【００１５】上記本発明の超電導接合構造体では、基板
５はMgＯ（１００）基板であり、超電導領域１、２およ
び結合部３は、Bi2Sr2Ca2Cu3Ｏx 酸化物超電導薄膜で構
成されている。また、結合部３は10μｍ×５μｍの寸法
に形成されている。In the superconducting junction structure of the present invention, the substrate 5 is an MgO (100) substrate, and the superconducting regions 1 and 2 and the joint 3 are Bi 2 Sr 2 Ca 2 Cu 3 O x oxide superconducting thin films. It is configured. Further, the coupling portion 3 is formed to have a size of 10 μm × 5 μm.
【００１６】上記本発明の超電導接合構造体の作製工程
を説明する。まず、MgＯ（１００）基板５上にBi2Sr2Ca
2Cu3Ｏx 酸化物超電導薄膜を形成する。成膜方法として
はスパッタリング法が好ましい。成膜条件を以下に示
す。 基板温度 630℃ スパッタリングガス Ar ８SCCM Ｏ2 ４SCCM 圧力 ５×10-2Torr 膜厚 200nmThe steps of producing the superconducting junction structure of the present invention will be described. First, on the MgO (100) substrate 5, Bi 2 Sr 2 Ca
2 Cu 3 O x oxide superconducting thin film is formed. A sputtering method is preferable as a film forming method. The film forming conditions are shown below. Substrate temperature 630 ℃ Sputtering gas Ar 8SCCM O 2 4SCCM Pressure 5 × 10 -2 Torr Film thickness 200nm
【００１７】上記のように成膜したBi2Sr2Ca2Cu3Ｏx 酸
化物超電導薄膜を構成する結晶方向を調べ、超電導電流
が結晶中のCu−Ｏ面に垂直に流れるよう超電導接合構造
体の方向を定める。次いで、反応性イオンエッチングを
使用して、上記のBi2Sr2Ca2Cu3Ｏx 酸化物超電導薄膜を
図１に示す形状に加工し、本発明の超電導接合構造体が
完成する。このように作製された本発明の超電導接合構
造体は、元来単一の酸化物超電導薄膜であったので、第
１および第２の超電導領域の特性が揃っており、また、
超電導領域と結合部との間に界面が存在しない。従っ
て、不要な抵抗成分や超電導接合が内部に存在すること
がない。The crystal direction of the Bi 2 Sr 2 Ca 2 Cu 3 O x oxide superconducting thin film formed as described above is investigated, and the superconducting junction structure is formed so that the superconducting current flows perpendicularly to the Cu-O plane in the crystal. Determine the body direction. Then, the above Bi 2 Sr 2 Ca 2 Cu 3 O x oxide superconducting thin film is processed into the shape shown in FIG. 1 by using reactive ion etching to complete the superconducting junction structure of the present invention. Since the superconducting junction structure of the present invention thus produced was originally a single oxide superconducting thin film, the characteristics of the first and second superconducting regions were uniform, and
There is no interface between the superconducting region and the joint. Therefore, unnecessary resistance components and superconducting junctions do not exist inside.
【００１８】上記本発明の超電導接合構造体を使用した
ジョセフソン素子の特性を測定した。85Ｋに冷却し、周
波数15ＧHz、出力0.2 ｍＷのマイクロ波を印加したとこ
ろ、31μＶの倍数の電圧点でシャピロステップが観測さ
れ、ジョセフソン結合が実現していることが確認され
た。The characteristics of the Josephson device using the above-mentioned superconducting junction structure of the present invention were measured. When cooled to 85K and a microwave of 15 GHz frequency and 0.2 mW output was applied, Shapiro step was observed at a voltage point of a multiple of 31 μV, confirming that Josephson coupling was realized.
【００１９】[0019]
【発明の効果】以上説明したように、本発明に従うと、
新規な構成の超電導接合構造体を酸化物超電導体により
実現できる。本発明の超電導接合構造体は、同時に成長
した１枚の酸化物超電導薄膜から構成されている。ま
た、本発明の超電導接合構造体は、従来必要とされた微
細加工を行うことなく容易に作製することが可能であ
る。本発明により、超電導技術の電子デバイスへの応用
がさらに促進される。As described above, according to the present invention,
A novel superconducting junction structure can be realized by using an oxide superconductor. The superconducting junction structure of the present invention is composed of one oxide superconducting thin film grown at the same time. Further, the superconducting junction structure of the present invention can be easily manufactured without performing the fine processing conventionally required. The present invention further facilitates the application of superconducting technology to electronic devices.
【図１】本発明の超電導接合構造体の平面図である。FIG. 1 is a plan view of a superconducting junction structure of the present invention.
１、２ 超電導領域 ３ 結合部 ５ 基板 1, 2 Superconducting region 3 Coupling part 5 Substrate
Claims (1)
に障壁が発生するよう弱く結合させて構成される弱結合
型超電導接合を実現している構造体において、前記第１
および第２の超電導領域が、一体のｃ軸が膜面に平行な
酸化物超電導薄膜で形成され、前記障壁が前記酸化物超
電導薄膜を構成する酸化物超電導体結晶のCu−Ｏ面間の
結晶面であることを特徴とする超電導接合構造体。1. A structure that realizes a weak-coupling type superconducting junction configured by weakly bonding first and second superconducting regions so as to generate a barrier at a bonding portion.
And the second superconducting region is formed of an oxide superconducting thin film whose c-axis is parallel to the film surface, and the barrier is a crystal between Cu-O planes of the oxide superconducting crystal that constitutes the oxide superconducting thin film. A superconducting junction structure characterized by being a surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4118014A JPH05291632A (en) | 1992-04-10 | 1992-04-10 | Superconductive junction structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4118014A JPH05291632A (en) | 1992-04-10 | 1992-04-10 | Superconductive junction structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05291632A true JPH05291632A (en) | 1993-11-05 |
Family
ID=14725926
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4118014A Withdrawn JPH05291632A (en) | 1992-04-10 | 1992-04-10 | Superconductive junction structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05291632A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19629583A1 (en) * | 1996-07-23 | 1998-01-29 | Dornier Gmbh | Emitter and / or detector component for submillimeter-wave radiation and method for its production |
| US6348699B1 (en) | 1996-07-23 | 2002-02-19 | Oxxel Oxide Electronics Technology Gmbh | Josephson junction array device, and manufacture thereof |
-
1992
- 1992-04-10 JP JP4118014A patent/JPH05291632A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19629583A1 (en) * | 1996-07-23 | 1998-01-29 | Dornier Gmbh | Emitter and / or detector component for submillimeter-wave radiation and method for its production |
| DE19629583C2 (en) * | 1996-07-23 | 2001-04-19 | Oxxel Oxide Electronics Techno | Emitter and / or detector device for submillimeter-wave radiation with a multiplicity of Josephson contacts, method for its production and uses of the device |
| US6348699B1 (en) | 1996-07-23 | 2002-02-19 | Oxxel Oxide Electronics Technology Gmbh | Josephson junction array device, and manufacture thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Application deemed to be withdrawn because no request for examination was validly filed |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19990706 |