JPH04318983A - Josephson junction element and manufacture thereof - Google Patents
Josephson junction element and manufacture thereofInfo
- Publication number
- JPH04318983A JPH04318983A JP3110808A JP11080891A JPH04318983A JP H04318983 A JPH04318983 A JP H04318983A JP 3110808 A JP3110808 A JP 3110808A JP 11080891 A JP11080891 A JP 11080891A JP H04318983 A JPH04318983 A JP H04318983A
- Authority
- JP
- Japan
- Prior art keywords
- substrate surface
- ybco
- josephson junction
- thin film
- substrate
- 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
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 229910021521 yttrium barium copper oxide Inorganic materials 0.000 claims abstract description 68
- 239000000758 substrate Substances 0.000 claims abstract description 63
- 239000010409 thin film Substances 0.000 claims abstract description 56
- 239000013078 crystal Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims description 14
- 239000002994 raw material Substances 0.000 claims description 8
- 239000002887 superconductor Substances 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 238000005229 chemical vapour deposition Methods 0.000 claims description 3
- 238000007740 vapor deposition Methods 0.000 claims description 3
- 150000004696 coordination complex Chemical class 0.000 claims 2
- 238000001556 precipitation Methods 0.000 claims 1
- 239000000126 substance Substances 0.000 claims 1
- 239000012808 vapor phase Substances 0.000 claims 1
- 229910002370 SrTiO3 Inorganic materials 0.000 abstract description 4
- 239000010408 film Substances 0.000 abstract 2
- 230000015572 biosynthetic process Effects 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000001312 dry etching Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000001039 wet etching Methods 0.000 description 2
- 241000238366 Cephalopoda Species 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000002230 thermal chemical vapour deposition Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【０００１】0001
【従来の技術】Ｙ系超伝導体（ＹＢａ２Ｃｕ３Ｏ７−ｙ
：以下ＹＢＣＯと略す）は、液体窒素温度以上の超伝
導転移温度を有することから、超伝導デバイスの液体窒
素温度での動作が期待されている。[Prior art] Y-based superconductor (YBa2Cu3O7-y
(hereinafter abbreviated as YBCO) has a superconducting transition temperature higher than the liquid nitrogen temperature, so it is expected that a superconducting device can operate at the liquid nitrogen temperature.
【０００２】しかしＹＢＣＯは、セラミックス材料であ
るために脆く、従来の超伝導体に比べてコヒーレント長
が短いなどの特性を有している。このような特性により
従来の超伝導体で用いられていたポイントコンタクト型
やブッリジ型、トンネル接合型などのジョセフソン接合
の作製技術をそのままＹＢＣＯに適用する事は非常に困
難である。ＹＢＣＯでは従来の接合作製技術を改良した
様々な構造のジョセフソン接合が考案されている。However, since YBCO is a ceramic material, it is brittle and has characteristics such as a shorter coherence length than conventional superconductors. Due to these characteristics, it is extremely difficult to apply the fabrication technology of Josephson junctions such as point contact type, bridge type, and tunnel junction type used in conventional superconductors to YBCO as is. In YBCO, Josephson junctions of various structures have been devised by improving conventional junction fabrication techniques.
【０００３】すでに報告されているジョセフソン接合の
多くは、ＹＢＣＯの結晶粒界を用いたものである。当初
報告された結晶粒界による接合は、ＹＢＣＯ合成時に自
然に形成される結晶粒界を用いた接合であった。しかし
、結晶粒界の分布がランダムであるために特定の結晶粒
界にブッリジを形成することが困難であり、特性の再現
性や安定性に問題があった。Many of the Josephson junctions that have already been reported use YBCO grain boundaries. The bonding based on grain boundaries that was initially reported was a bonding using grain boundaries that are naturally formed during YBCO synthesis. However, since the distribution of grain boundaries is random, it is difficult to form bridges at specific grain boundaries, and there are problems with the reproducibility and stability of characteristics.
【０００４】特許出願平１−１６１８８０号では、酸化
物超伝導体の超伝導特性の異方性を利用したジョセフソ
ン接合が考案されている。臨界電流密度の大きい軸方向
が電流方向となるようにバンク部を形成し、バンク部の
間に臨界電流密度の小さい軸方向が電流方向となるよう
に構成して臨界電流密度の小さい軸方向の酸化物超伝導
結晶の構造自体がジョセフソン接合的になっていること
によりジョセフソン接合を構成することが述べられてい
る。しかし、臨界電流密度の小さい軸方向の酸化物超伝
導体の形成は、基板の面方位に関係するため任意の位置
にジョセフソン接合を形成することは難しい。[0004] Patent application No. 1-161880 devises a Josephson junction that utilizes the anisotropy of superconducting properties of oxide superconductors. The bank portion is formed so that the axial direction where the critical current density is high is the current direction, and the axial direction where the critical current density is low is formed between the bank portions so that the current direction is the axial direction where the critical current density is low. It has been stated that the structure of an oxide superconducting crystal itself is Josephson junction-like, thereby forming a Josephson junction. However, since the formation of an axial oxide superconductor with a small critical current density is related to the plane orientation of the substrate, it is difficult to form a Josephson junction at an arbitrary position.
【０００５】再現性や安定性を向上させるためＹＢＣＯ
に人工的な結晶粒界を形成し、この人工粒界を接合に用
いる方法も考案されている。ベース電極上に絶縁層を介
して反対方向の電極の一部が絶縁層上に重なるように二
つの電極を形成して両電極の接するエッジ部分を接合と
したエッジ型のジョセフソン接合がアプライド フィ
ジックス レターズ５６巻７号（１９９０年）６８６
頁から６８８頁（ＡｐｐｌｉｅｄＰｈｙｓｉｃｓ Ｌｅ
ｔｔｅｒｓ． Ｖｏｌ． ５６、Ｎｏ．７（１９９０）
ｐ６８６−６８８） に述べられている。エッジ接合は
、自然粒界を用いたジョセフソン接合と同じ様な特性を
示している。また、その動作温度は７７Ｋ以下である。[0005] In order to improve reproducibility and stability, YBCO
A method has also been devised in which artificial grain boundaries are formed in the material and these artificial grain boundaries are used for bonding. Applied Physics uses an edge-type Josephson junction in which two electrodes are formed on the base electrode with an insulating layer in between, with the electrodes facing in opposite directions partially overlapping the insulating layer, and the edge portions where the two electrodes touch are connected. Letters Vol. 56 No. 7 (1990) 686
Pages 688 (Applied Physics Le
tters. Vol. 56, No. 7 (1990)
p686-688). Edge junctions exhibit similar characteristics to Josephson junctions using natural grain boundaries. Moreover, its operating temperature is 77K or less.
【０００６】特願平１−２４１８７４号では、基板に傾
斜した面をつけてＹＢＣＯ薄膜を形成し、その部分のＹ
ＢＣＯ薄膜の配向を変化させて傾斜した面と平坦な面と
の境界上に人工粒界を形成し、その粒界を用いたジョセ
フソン接合が述べられている。また特願平１−２１８０
７７号では、二個の単結晶を結合したバイクリスタル基
板を用い、基板の接合界面上に形成される人工粒界を用
いたジョセフソン接合が述べられている。そのほか基板
に溝や段差を設けてＹＢＣＯ薄膜中に人工粒界を形成す
る方法なども提案されている。しかし、これらのジョセ
フソン接合では、いずれも基板を加工する工程が必要と
され、同一基板面上の任意の場所に複数個の接合を形成
する場合の基板加工は非常に難しいことが予測される。[0006] In Japanese Patent Application No. 1-241874, a YBCO thin film is formed on a substrate with an inclined surface, and the YBCO thin film on that portion is
A Josephson junction is described in which the orientation of a BCO thin film is changed to form an artificial grain boundary on the boundary between an inclined surface and a flat surface, and the grain boundary is used. Also, patent application No. 1-2180
No. 77 describes a Josephson junction using a bicrystal substrate in which two single crystals are bonded together and an artificial grain boundary formed on the bonding interface of the substrates. In addition, a method has been proposed in which grooves or steps are provided in the substrate to form artificial grain boundaries in the YBCO thin film. However, all of these Josephson junctions require a process to process the substrate, and it is predicted that substrate processing will be extremely difficult when forming multiple bonds at arbitrary locations on the same substrate surface. .
【０００７】[0007]
【発明が解決しようとする課題】本発明は前記した従来
技術の問題点に着目してなされたもので、特別な基板加
工を行わずに人工的に結晶粒界を形成させ、この結晶粒
界を接合とすることにより再現性や安定性に優れたジョ
セフソン接合を形成してスクイドやミクサー、ジョセフ
ソンＦＥＴ、電圧標準などに適用可能な特性の揃ったジ
ョセフソン接合素子およびその製造方法を提供すること
を目的としている。[Problems to be Solved by the Invention] The present invention has been made by focusing on the problems of the prior art described above. By forming a Josephson junction with excellent reproducibility and stability, we provide a Josephson junction element with uniform characteristics that can be applied to SQUIDs, mixers, Josephson FETs, voltage standards, etc., and a method for manufacturing the same. It is intended to.
【０００８】[0008]
【課題を解決するための手段および作用】本発明は、前
述した課題を解決するため、平坦な基板の同一基板表面
上に少なくとも基板面の垂直な方向においてＹＢＣＯの
結晶配向性が異なる２つ以上の連続したＹＢＣＯの領域
を順次設け、ＹＢＣＯの結晶配向性の不整合によりそれ
ぞれの領域のＹＢＣＯの境界に形成される結晶粒界にブ
リッジを形成してジョセフソン接合素子とするものであ
る。[Means and Effects for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides two or more YBCO crystals having different crystal orientations on the same flat substrate surface at least in the direction perpendicular to the substrate surface. Continuous YBCO regions are sequentially provided, and a bridge is formed at the grain boundary formed at the YBCO boundary in each region due to mismatching of the YBCO crystal orientation, thereby forming a Josephson junction element.
【０００９】より具体的な本発明のジョセフソン接合素
子は、平坦な基板の同一基板面上に、基板面に垂直な方
向において一定の結晶配向性を有するＹＢＣＯの領域を
形成させる。さらに前記領域のＹＢＣＯとは結晶配向性
が異なり、基板面に垂直な方向において一定の結晶配向
性を有し、少なくとも接合を必要と部分が前記領域と連
続しているＹＢＣＯの領域を形成する。各領域における
ＹＢＣＯの結晶配向性は、ＹＢＣＯ形成時の条件により
制御され、エピタキシャル成長可能な基板を用いて制御
してもよい。More specifically, in the Josephson junction device of the present invention, a YBCO region having a constant crystal orientation in the direction perpendicular to the substrate surface is formed on the same plane of a flat substrate. Further, a YBCO region is formed which has a crystal orientation different from that of the YBCO in the region, has a constant crystal orientation in a direction perpendicular to the substrate surface, and is continuous with the region at least in a portion requiring bonding. The crystal orientation of YBCO in each region is controlled by the conditions during YBCO formation, and may be controlled using a substrate capable of epitaxial growth.
【００１０】結晶配向性の異なるＹＢＣＯのそれぞれの
領域が基板面に垂直方向に形成させるとき、場合によっ
ては結晶配向性の異なるＹＢＣＯ領域が基板面に平行な
方向にお互いに重なり合い、その部分において電気的な
短絡がある場合を生じる。かかる場合には、それぞれの
領域の重り合った部分の間に基板面に平行な方向に中間
層を形成して短絡を防ぐことができる。中間層は絶縁層
として作用し、積層時にＹＢＣＯと反応してＹＢＣＯの
超伝導特性を劣化させないものであればよい。以上のよ
うな基板の同一平面上に形成されたＹＢＣＯの結晶配向
性の不整合による結晶粒界が接合となるようにブリッジ
を形成してジョセフソン接合素子とする。[0010] When YBCO regions with different crystal orientations are formed in a direction perpendicular to the substrate surface, in some cases the YBCO regions with different crystal orientations overlap each other in the direction parallel to the substrate surface, and electricity is generated in that portion. This may occur if there is a short circuit. In such a case, an intermediate layer can be formed between the overlapping portions of the respective regions in a direction parallel to the substrate surface to prevent short circuits. The intermediate layer may act as an insulating layer and may be any layer that does not react with YBCO during stacking and deteriorate the superconducting properties of YBCO. A Josephson junction element is obtained by forming a bridge so that the crystal grain boundaries due to mismatched crystal orientations of YBCO formed on the same plane of the substrate serve as junctions.
【００１１】本発明のジョセフソン接合素子の製造方法
は、Ｙ、ＢａおよびＣｕのβ−ジケトン錯体を原料物質
とした熱化学気相析出法により基板表面上に結晶配向性
を有するＹＢＣＯ薄膜の領域を基板面上に形成させ、さ
らに同様な原料物質を用いた熱化学気相析出法によりジ
ョセフソン接合を形成する領域に前記領域と連続し、さ
らに前記領域のＹＢＣＯ薄膜とは結晶配向性の異なるＹ
ＢＣＯ薄膜を形成させる。各領域におけるＹＢＣＯ薄膜
の配向性は、ＹＢＣＯ薄膜形成時のＹ、ＢａおよびＣｕ
のβ−ジケトン金属錯体原料蒸気の初期濃度を変化させ
ることにより制御され、またエピタキシャル成長可能な
基板を用い制御してもよい。結晶各領域における薄膜の
結晶配向性は、基板面に対してＹＢＣＯのｃ軸、ａ軸あ
るいは〔１１０〕軸が垂直に配向したものである。各領
域における配向軸は、これら配向軸のいずれかの組み合
わせからなるものであればよく、電極部となる領域のＹ
ＢＣＯ薄膜は、接合部以外に存在する結晶粒界に補足さ
れる磁束に起因すると考えられる雑音を低減するためエ
ピタキシャル成長させることが好ましい。結晶配向性の
異なるＹＢＣＯ薄膜のそれぞれの領域が、基板面に平行
な方向に接する部分において電気的な短絡がある場合に
は、それぞれの領域が接するＹＢＣＯ薄膜の間に絶縁層
として働く中間層を形成する。The method for manufacturing a Josephson junction device of the present invention is to deposit a region of a YBCO thin film having crystal orientation on a substrate surface by thermochemical vapor deposition using a β-diketone complex of Y, Ba and Cu as raw materials. is formed on the substrate surface, and is continuous with the region in which the Josephson junction is to be formed by thermal chemical vapor deposition using the same raw material, and has a crystal orientation different from that of the YBCO thin film in the region. Y
A BCO thin film is formed. The orientation of the YBCO thin film in each region is determined by Y, Ba and Cu during the formation of the YBCO thin film.
It is controlled by changing the initial concentration of the β-diketone metal complex raw material vapor, and may also be controlled by using a substrate capable of epitaxial growth. The crystal orientation of the thin film in each crystal region is such that the c-axis, a-axis, or [110] axis of YBCO is oriented perpendicularly to the substrate surface. The orientation axis in each region may be any combination of these orientation axes, and the
The BCO thin film is preferably epitaxially grown in order to reduce noise that is considered to be caused by magnetic flux captured by grain boundaries that exist outside the junction. If there is an electrical short circuit in the part where each region of the YBCO thin film with different crystal orientation touches in a direction parallel to the substrate surface, an intermediate layer that acts as an insulating layer is placed between the YBCO thin films where each region contacts. Form.
【００１２】以上のような方法により基板上にＹＢＣＯ
薄膜の結晶配向性の不整合による結晶粒界が形成され、
この結晶粒界が接合となるようにブリッジを形成する。
ブリッジはウエットエッチングあるいはドライエッチン
グ等の通常の方法によって形成すればよく、その形状や
サイズは、必要とされるジョセフソン接合素子に合わせ
任意である。[0012] By the above method, YBCO is deposited on the substrate.
Grain boundaries are formed due to mismatched crystal orientation in the thin film,
A bridge is formed so that this grain boundary becomes a junction. The bridge may be formed by a conventional method such as wet etching or dry etching, and its shape and size are arbitrary depending on the Josephson junction element required.
【００１３】[0013]
【作用】本発明によれば、基板の同一平面上のＹＢＣＯ
の人工的な結晶配向性の不整合による結晶粒界を接合に
用いることによって再現性や安定性に優れたジョセフソ
ン接合素子を提供することができる。また特別な基板加
工を必要としないことから基板上の任意の位置に複数個
のジョセフソン接合素子を作製することができ、基板上
のＹＢＣＯ薄膜の配向性の調整によって電極部の電流の
流れ易い方向を、基板面に平行な方向あるいは垂直な方
向いずれの方向も必要に応じて設定することができる。
さらに熱化学気相析出法では、超伝導特性に優れた結晶
配向性の異なる薄膜を同一温度で形成することが可能で
あるため、結晶配向性の不整合による結晶粒界の部分に
おいて薄膜の拡散や再結晶化が起こりにくく、シャープ
な結晶粒界を形成でき、より再現性や安定性に優れたジ
ョセフソン接合素子を製造することができる。[Operation] According to the present invention, YBCO on the same plane of the substrate
A Josephson junction element with excellent reproducibility and stability can be provided by using crystal grain boundaries due to artificial crystal orientation mismatch in the junction. Additionally, since no special substrate processing is required, multiple Josephson junction elements can be fabricated at any location on the substrate, and by adjusting the orientation of the YBCO thin film on the substrate, current can easily flow through the electrodes. The direction can be set as necessary, either parallel or perpendicular to the substrate surface. Furthermore, with thermochemical vapor deposition, it is possible to form thin films with excellent superconducting properties and different crystal orientations at the same temperature. It is possible to produce a Josephson junction element that is less prone to crystallization and recrystallization, can form sharp grain boundaries, and has better reproducibility and stability.
【００１４】[0014]
【実施例】以下、本発明の実施例を図を参照して説明す
る。図１及び２は、本発明の一実施例のジョセフソン接
合素子を示す。図１は平面図であり、図２はその断面図
である。ＳｒＴｉＯ３（１００） 単結晶基板１上の基
板面の半分に基板面に対して垂直にｃ軸が配向したＹＢ
ＣＯ薄膜２が形成され、その反対側の基板面上へ基板面
に対してａ軸が垂直に配向したＹＢＣＯ薄膜３が形成さ
れる。この結果、ｃ軸配向したＹＢＣＯ薄膜２とａ軸配
向したＹＢＣＯ薄膜との配向性の不整合によって結晶粒
界４が形成され、この結晶粒界４上にブリッジ形状のパ
ターンを形成してジョセフソン接合が形成される。[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. 1 and 2 illustrate a Josephson junction device according to one embodiment of the invention. FIG. 1 is a plan view, and FIG. 2 is a cross-sectional view thereof. SrTiO3 (100) YB with c-axis oriented perpendicular to the substrate surface on half of the substrate surface on the single crystal substrate 1
A CO thin film 2 is formed, and a YBCO thin film 3 whose a-axis is oriented perpendicular to the substrate surface is formed on the opposite substrate surface. As a result, a crystal grain boundary 4 is formed due to the mismatch in orientation between the c-axis oriented YBCO thin film 2 and the a-axis oriented YBCO thin film, and a bridge-shaped pattern is formed on this crystal grain boundary 4 to form a Josephson A bond is formed.
【００１５】具体的には、ＹＢＣＯ薄膜２はＹ、Ｂａ、
Ｃｕの（ｔｈｄ）錯体を原料物質とした化学気相析出法
により基板面の半分をメタルマスクして基板温度８５０
℃、炉内圧力１０Ｔｏｒｒで形成され、ＹＢＣＯ薄膜３
はＹＢＣＯ薄膜２上をメタルマスクし、ＹＢＣＯ薄膜合
成初期におけるＢａ原料の濃度を高くして他の条件はＹ
ＢＣＯ薄膜２合成時と同様な条件により形成する。図３
にＹＢＣＯ薄膜２の部分を中心にＸ線が照射されるよう
にして測定したＸ線回折図形を示す。図４にはＹＢＣＯ
薄膜３の部分を中心にＸ線が照射されるようにして測定
したＸ線回折図形を示す。基板上のＹＢＣＯ薄膜２は（
００１）ピークの回折強度が強く、ＹＢＣＯ薄膜３は（
ｈ００）ピークの回折強度が強く、ＹＢＣＯ薄膜２はｃ
軸配向を示しており、ＹＢＣＯ薄膜３はａ軸配向を示し
ている。ＹＢＣＯ薄膜２とＹＢＣＯ薄膜３との境界部分
を挟むように電圧端子を設けて４端子法によって測定し
た薄膜の電気抵抗の温度依存性を図５に示す。薄膜は液
体窒素温度以上で抵抗ゼロを示している。ＹＢＣＯ薄膜
２とＹＢＣＯ薄膜３との境界部分には、ＹＢＣＯ薄膜の
配向性の不整合によって結晶粒界４が形成され、結晶粒
界４上にドライエッチングによってブリッジを形成する
。このブッリジに存在する結晶粒界４によって超伝導特
性が弱められて接合が形成される。Specifically, the YBCO thin film 2 contains Y, Ba,
Half of the substrate surface is covered with a metal mask using a chemical vapor deposition method using Cu (thd) complex as a raw material, and the substrate temperature is 850.
The YBCO thin film 3 was formed at ℃ and 10 Torr pressure in the furnace.
The other conditions were YBCO thin film 2 was covered with a metal mask, and the concentration of Ba raw material was increased at the initial stage of YBCO thin film synthesis.
It is formed under the same conditions as when synthesizing the BCO thin film 2. Figure 3
2 shows an X-ray diffraction pattern measured with X-rays being irradiated mainly on the YBCO thin film 2. Figure 4 shows YBCO
An X-ray diffraction pattern measured while irradiating X-rays centered on the thin film 3 is shown. The YBCO thin film 2 on the substrate is (
001) The diffraction intensity of the peak is strong, and the YBCO thin film 3 has (
h00) The diffraction intensity of the peak is strong, and the YBCO thin film 2 is c
The YBCO thin film 3 has an a-axis orientation. FIG. 5 shows the temperature dependence of the electrical resistance of the thin film measured by a four-terminal method with voltage terminals provided across the boundary between the YBCO thin film 2 and the YBCO thin film 3. The thin film exhibits zero resistance above liquid nitrogen temperature. At the boundary between the YBCO thin film 2 and the YBCO thin film 3, a crystal grain boundary 4 is formed due to misalignment of the orientation of the YBCO thin film, and a bridge is formed on the crystal grain boundary 4 by dry etching. The superconducting properties are weakened by the grain boundaries 4 existing in this bridge, and a junction is formed.
【００１６】図６及び図７は、他の実施例のジョセフソ
ン接合素子を示す。図６は平面図であり、図７はその断
面図である。ＳｒＴｉＯ３（１００） 単結晶基板１上
の両側に基板面に対して垂直にｃ軸が配向したＹＢＣＯ
薄膜２が形成され、その間の基板面上へ基板面に対して
ａ軸が垂直に配向したＹＢＣＯ薄膜３が形成される。ｃ
軸配向およびａ軸配向したＹＢＣＯ薄膜の形成は第一の
実施例と同様な方法によって形成される。本実施例は、
ＹＢＣＯ薄膜の配向性の不整合による結晶粒界４が基板
上に２ヶ所形成される。図６の平面図では一方の結晶粒
界４上をパターンニングしてブッリジを形成したがいず
れの結晶粒界を用いてもよく、両方の結晶粒界を用いて
複数個のジョセフソン接合素子を形成することもできる
。FIGS. 6 and 7 show other embodiments of Josephson junction devices. FIG. 6 is a plan view, and FIG. 7 is a cross-sectional view thereof. SrTiO3 (100) YBCO with the c-axis oriented perpendicular to the substrate surface on both sides of the single crystal substrate 1
A thin film 2 is formed, and a YBCO thin film 3 whose a-axis is oriented perpendicularly to the substrate surface is formed on the substrate surface between them. c.
The axially oriented and a-axis oriented YBCO thin films are formed by the same method as in the first embodiment. In this example,
Two grain boundaries 4 are formed on the substrate due to misalignment of the orientation of the YBCO thin film. In the plan view of FIG. 6, a bridge is formed by patterning on one grain boundary 4, but either grain boundary may be used, and both grain boundaries may be used to form a plurality of Josephson junction elements. It can also be formed.
【００１７】本実施例では、ｃ軸配向した薄膜をメタル
マスクを用いて薄膜合成時に基板面の半分に形成したが
、基板の全面にｃ軸配向したＹＢＣＯ薄膜を合成後にウ
ェットエッチングあるいはドライエッチング等の方法に
よって形成してもよく、またその形状やサイズ、基板上
の位置も必要とされるジョセフソン接合素子に合わせ任
意に形成される。さらに基板上に形成されるＹＢＣＯ薄
膜の配向性は、本実施例に限定されるものではなく、Ｙ
ＢＣＯ薄膜の配向性の不整合によって結晶粒界が形成さ
れればよく、化学気相析出法によって形成されるｃ軸配
向、ａ軸配向、〔１１０ 〕軸配向の薄膜の組み合わせ
であればよい。In this example, a c-axis oriented thin film was formed on half of the substrate surface using a metal mask during thin film synthesis, but a c-axis oriented YBCO thin film was formed on the entire surface of the substrate by wet etching, dry etching, etc. after synthesis. The shape, size, and position on the substrate can be arbitrarily formed according to the required Josephson junction element. Furthermore, the orientation of the YBCO thin film formed on the substrate is not limited to this example;
It is sufficient that the grain boundaries are formed due to misalignment of the orientation of the BCO thin film, and any combination of thin films with c-axis orientation, a-axis orientation, and [110]-axis orientation formed by chemical vapor deposition may be used.
【００１８】[0018]
【効果】以上述べたように本発明によれば、結晶配向性
の不整合による人工的な結晶粒界を接合としたことによ
り、目的とする基板面上の任意の位置に安定性や再現性
に優れたジョセフソン接合素子を提供することができる
。また複雑な工程を必要とせずに容易に複数個のジョセ
フソン接合を形成することができ、電圧標準などの多く
のジョセフソン接合を必要とする素子の作製が可能とな
る。[Effects] As described above, according to the present invention, by using artificial grain boundaries due to mismatched crystal orientation as a bond, it is possible to achieve stability and reproducibility at any position on the target substrate surface. It is possible to provide an excellent Josephson junction element. Furthermore, a plurality of Josephson junctions can be easily formed without the need for complicated processes, making it possible to manufacture devices that require many Josephson junctions, such as voltage standards.
【図１】本発明の一実施例のジョセフソン接合素子を示
す平面図である。FIG. 1 is a plan view showing a Josephson junction device according to an embodiment of the present invention.
【図２】図１に示されたジョセフソン接合素子のＡ−Ａ
′部の断面図である。FIG. 2: A-A of the Josephson junction device shown in FIG. 1.
FIG.
【図３】図１に示されたＹＢＣＯ薄膜２のＸ線回折図で
ある。3 is an X-ray diffraction diagram of the YBCO thin film 2 shown in FIG. 1. FIG.
【図４】図１に示されたＹＢＣＯ薄膜３のＸ線回折図で
ある。4 is an X-ray diffraction diagram of the YBCO thin film 3 shown in FIG. 1. FIG.
【図５】図１に示されたジョセフソン接合素子に適用さ
れるＹＢＣＯ薄膜の電気抵抗の温度依存性を示す図であ
る。FIG. 5 is a diagram showing the temperature dependence of the electrical resistance of the YBCO thin film applied to the Josephson junction device shown in FIG. 1;
【図６】本発明の別の実施例のジョセフソン接合素子を
示す平面図である。FIG. 6 is a plan view of a Josephson junction device according to another embodiment of the present invention.
【図７】図６に示されたジョセフソン接合素子のＢ−Ｂ
′部の断面図である。FIG. 7: B-B of the Josephson junction device shown in FIG.
FIG.
１ ＳｒＴｉＯ３基板 ２ ＹＢＣＯ薄膜 ３ ＹＢＣＯ薄膜 ４ 結晶粒界 1 SrTiO3 substrate 2 YBCO thin film 3 YBCO thin film 4 Grain boundaries
Claims (5)
導体の結晶粒界を接合とするジョセフソン接合素子にお
いて、平坦な基板面上に少なくとも基板面に垂直な方向
に対して結晶配向性の異なる２つ以上の連続したＹＢａ
２Ｃｕ３Ｏ７−ｙ の領域を順次設け、それぞれの領域
の境界に形成される結晶粒界を接合としたことを特徴と
するジョセフソン接合素子。[Claim 1] In a Josephson junction element in which the junction is a crystal grain boundary of a YBa2Cu3O7-y oxide superconductor, two junctions having different crystal orientations at least in a direction perpendicular to the substrate surface are formed on a flat substrate surface. Consecutive YBa of
1. A Josephson junction element characterized in that regions of 2Cu3O7-y are sequentially provided and the grain boundaries formed at the boundaries of each region serve as junctions.
けるＹＢａ２Ｃｕ３Ｏ７−ｙ の基板面に垂直な方向で
の結晶配向性が、ｃ軸、ａ軸あるいは〔１１０〕軸のい
ずれかの組み合わせからなることを特徴とする請求項１
記載のジョセフソン接合素子。2. The crystal orientation of YBa2Cu3O7-y in each region on a flat substrate surface in a direction perpendicular to the substrate surface is a combination of c-axis, a-axis, or [110] axis. Claim 1 characterized by
Josephson junction device as described.
Ｂａ２Ｃｕ３Ｏ７−ｙ において、基板面に垂直な方向
に接するＹＢａ２Ｃｕ３Ｏ７−ｙ 上に、基板面に平行
な方向に領域の境界より絶縁層となる中間層を有するこ
とを特徴とする請求項１記載のジョセフソン接合素子。[Claim 3] Y of each region on a flat substrate surface
2. The Josephson according to claim 1, wherein the Ba2Cu3O7-y has an intermediate layer serving as an insulating layer extending from the region boundary in a direction parallel to the substrate surface on the YBa2Cu3O7-y in contact with the substrate surface in a direction perpendicular to the substrate surface. Junction element.
およびＣｕのβ−ジケトン金属錯体を原料とした熱化学
気相析出法により形成される薄膜であることを特徴とす
る請求項１記載のジョセフソン接合素子。[Claim 4] YBa2Cu3O7-y is Y, Ba
2. The Josephson junction device according to claim 1, wherein the thin film is formed by a thermochemical vapor deposition method using a β-diketone metal complex of Cu and Cu as raw materials.
ＢａおよびＣｕのβ−ジケトン金属錯体を含有する金属
錯体原料を用いて化学気相析出法により垂直方向に結晶
配向したＹＢａ２Ｃｕ３Ｏ７−ｙ を形成させ、更に該
金属錯体原料の初期濃度を変化させ、化学気相析出法に
より該領域とは異なる結晶配合性のＹＢａ２Ｃｕ３Ｏ７
−ｙ を基板に垂直方向に該領域に形成させることを特
徴とする請求項１記載のジョセフソン接合素子の製造方
法。5. In some areas on the flat substrate surface, Y,
Using a metal complex raw material containing a β-diketone metal complex of Ba and Cu, vertically oriented YBa2Cu3O7-y is formed by chemical vapor deposition, and the initial concentration of the metal complex raw material is changed, and chemical YBa2Cu3O7 with a crystal composition different from that in the region by vapor phase precipitation method
2. The method of manufacturing a Josephson junction device according to claim 1, wherein -y is formed in the region in a direction perpendicular to the substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3110808A JPH04318983A (en) | 1991-04-17 | 1991-04-17 | Josephson junction element and manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3110808A JPH04318983A (en) | 1991-04-17 | 1991-04-17 | Josephson junction element and manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04318983A true JPH04318983A (en) | 1992-11-10 |
Family
ID=14545186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3110808A Pending JPH04318983A (en) | 1991-04-17 | 1991-04-17 | Josephson junction element and manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04318983A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0756335A1 (en) * | 1995-07-24 | 1997-01-29 | International Superconductivity Technology Center | Josephson device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58156608U (en) * | 1982-04-13 | 1983-10-19 | 冨士シ−ル工業株式会社 | Shrink label attachment device |
| JPS58180105U (en) * | 1982-05-25 | 1983-12-01 | イ−・デ−・エム・株式会社 | Heat-sensitive adhesive label pasting device |
-
1991
- 1991-04-17 JP JP3110808A patent/JPH04318983A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58156608U (en) * | 1982-04-13 | 1983-10-19 | 冨士シ−ル工業株式会社 | Shrink label attachment device |
| JPS58180105U (en) * | 1982-05-25 | 1983-12-01 | イ−・デ−・エム・株式会社 | Heat-sensitive adhesive label pasting device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0756335A1 (en) * | 1995-07-24 | 1997-01-29 | International Superconductivity Technology Center | Josephson device |
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