JPH02206183A - Josephson junction and manufacture thereof - Google Patents
Josephson junction and manufacture thereofInfo
- Publication number
- JPH02206183A JPH02206183A JP1028000A JP2800089A JPH02206183A JP H02206183 A JPH02206183 A JP H02206183A JP 1028000 A JP1028000 A JP 1028000A JP 2800089 A JP2800089 A JP 2800089A JP H02206183 A JPH02206183 A JP H02206183A
- Authority
- JP
- Japan
- Prior art keywords
- film
- oxide superconductor
- josephson junction
- conducting layer
- normal conducting
- 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 6
- 239000002887 superconductor Substances 0.000 claims abstract description 29
- 239000000758 substrate Substances 0.000 claims abstract description 13
- 238000003776 cleavage reaction Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 5
- 230000007017 scission Effects 0.000 claims description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 abstract description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 abstract description 3
- 239000010931 gold Substances 0.000 abstract description 3
- 229910052737 gold Inorganic materials 0.000 abstract description 3
- 238000000151 deposition Methods 0.000 abstract description 2
- 229910052697 platinum Inorganic materials 0.000 abstract description 2
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007666 vacuum forming Methods 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
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少なくとも一方の電極に持つ
５−Ｎ−９型ジョセフソン接合及びその製造方法に関す
る。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a 5-N-9 type Josephson junction having an oxide superconductor in at least one electrode and a method for manufacturing the same.
高温酸化物超伝導体は超伝導コヒーレンス長が約数ｎｍ
と大変短いので、これを電極にしたジョセフソン接合は
、５−Ｉ−３型よりも５−Ｎ−８型の方が作りやす・い
と考えられている。従来この種の５−Ｎ−３接合は第４
図に示した断面構造を持つものが作られていた。図中、
１は酸化物超伝導体膜、２は基板、３は対向電極、５は
常伝導層である。酸化物超伝導体膜１と対向電極３との
超伝導オーダパラメータは常伝導層５の中まで近接効果
により侵入するので、この常伝導層５が十分に薄ければ
画電極はジョセフソン結合する。この常伝導層の厚さは
近接効果によりコヒーレンス長ξＮと同じオーダーであ
ることが必要であり、極低温では通常ξＮ２１庫である
。The superconducting coherence length of high-temperature oxide superconductors is approximately several nm.
Therefore, it is thought that it is easier to make a Josephson junction using this as an electrode in the 5-N-8 type than in the 5-I-3 type. Conventionally, this type of 5-N-3 junction
A device with the cross-sectional structure shown in the figure was manufactured. In the figure,
1 is an oxide superconductor film, 2 is a substrate, 3 is a counter electrode, and 5 is a normal conductive layer. The superconducting order parameters of the oxide superconductor film 1 and the counter electrode 3 penetrate into the normal conducting layer 5 due to the proximity effect, so if the normal conducting layer 5 is sufficiently thin, the picture electrode will undergo Josephson coupling. . The thickness of this normal conducting layer needs to be of the same order as the coherence length ξN due to the proximity effect, and is usually ξN21 at extremely low temperatures.
ところで、Ｙｌ Ｂａｚ Ｃｕ３０７−ｓに代表される
１−２−３相化合物やＢ１−５ｒ−Ｃａ−Ｃｕ−０，Ｔ
Ｑ−Ｂａ−Ｃａ−Ｃｕ−０などの高温酸化物超伝導体の
自然に形成されたその表面は、非超伝導物質である。通
常のパックスバッタ法などによる表面のクリーニングは
、超伝導体の結晶にイオンダメージを与えるので効果が
ない。したがってこのような非超伝導な表面に、第４図
のように５−Ｎ−５接合を作っても、酸化物超伝導体膜
１と常伝導層５間の清浄なコンタクトがとれないので、
得られたジョセフソン接合の特性は、理想的な５−Ｎ−
５接合特性からほど遠いものであった。By the way, 1-2-3 phase compounds represented by Yl Baz Cu307-s and B1-5r-Ca-Cu-0,T
The naturally formed surface of high temperature oxide superconductors such as Q-Ba-Ca-Cu-0 is a non-superconducting material. Cleaning the surface using the usual Paxbatter method is ineffective because it damages the superconductor crystals with ions. Therefore, even if a 5-N-5 junction is made on such a non-superconducting surface as shown in FIG. 4, clean contact cannot be made between the oxide superconductor film 1 and the normal conductive layer 5.
The characteristics of the obtained Josephson junction are those of the ideal 5-N-
5 junction characteristics.
本発明の目的は上記課題を解決したジョセフソン接合と
その製造方法を提供することにある。An object of the present invention is to provide a Josephson junction that solves the above problems and a method for manufacturing the same.
上記目的を達成するため、本発明によるジョセフソン接
合においては、酸化物超伝導体膜の膜側壁劈開面上に成
膜された常伝導層を介して前記酸化物超伝導体膜と前記
常伝導層上に作られた超伝導対向電極膜とをジョセフソ
ン結合させものである。In order to achieve the above object, in the Josephson junction according to the present invention, the oxide superconductor film and the normal conductor This layer is made by Josephson coupling with a superconducting counter electrode film formed on the layer.
本発明のジョセフソン接合は、基板上に成膜されている
酸化物超伝導体膜を低温真空環境下において劈開し、得
られた膜側壁劈開面上に、前記低温真空環境下において
常伝導層及び超伝導対向電極膜を順次成膜する製造方法
によって得られる。In the Josephson junction of the present invention, an oxide superconductor film formed on a substrate is cleaved in a low-temperature vacuum environment, and a normal conductive layer is placed on the resulting film sidewall cleavage plane in the low-temperature vacuum environment. and a manufacturing method in which superconducting counter electrode films are sequentially formed.
酸化物超伝導体を低温環境で劈開すると清浄な酸化物の
表面を露出させることができる。これは低温環境下では
化学反応速度が大変遅くなるので、新しく露出した表面
が劣化しないからである。このような状態でこの清浄面
に常伝導層を成膜することにより、清浄なＳ−Ｎ界面が
得られる。その手順を第３図（ａ）〜（ｃ）に示す。図
中、１は酸化物超伝導体膜、２は基板、４は膜側壁臂開
面、５は常伝導層、８は溝である。第３図（ａ）に示し
たような酸化物超伝導体膜１が成膜されている基板２を
真空装置内に入れ、低温状態にする。これは液体窒素ト
ラップ付きのサンプルホルダーなどの手段を用いて実現
できる。このような環境中で基板２に圧力をかけ、基板
２に予め作っである溝８に沿って基板２及び超伝導体膜
１を劈開する。すると第３図（ｂ）に示す清浄な膜側壁
臂開面４が露出する。この露出した劈開面４は、基板２
が低温状態にあるので、化学変化や表面の酸素の真空中
への脱出が起らない。このような清浄な状態で、第３図
（ｃ）に示した矢印の成膜方向に沿って常伝導層５を真
空成膜すると、清浄なＳ−Ｎ界面が得られる。したがっ
てこの上にさらに超伝導対向電極を成膜することにより
５−Ｎ−５ジョセフソン接合が形成される。By cleaving an oxide superconductor in a low-temperature environment, a clean oxide surface can be exposed. This is because the chemical reaction rate is very slow in a low-temperature environment, so the newly exposed surface does not deteriorate. By forming a normal conductive layer on this clean surface in such a state, a clean S-N interface can be obtained. The procedure is shown in FIGS. 3(a) to 3(c). In the figure, 1 is an oxide superconductor film, 2 is a substrate, 4 is a side wall opening of the film, 5 is a normal conductive layer, and 8 is a groove. A substrate 2 on which an oxide superconductor film 1 as shown in FIG. 3(a) is formed is placed in a vacuum apparatus and brought to a low temperature state. This can be achieved using means such as a sample holder with a liquid nitrogen trap. In such an environment, pressure is applied to the substrate 2 to cleave the substrate 2 and the superconductor film 1 along the grooves 8 previously formed in the substrate 2. Then, a clean membrane side wall opening surface 4 shown in FIG. 3(b) is exposed. This exposed cleavage plane 4 is located on the substrate 2.
Since it is in a low temperature state, chemical changes and surface oxygen escape into the vacuum do not occur. In such a clean state, if the normal conductive layer 5 is vacuum-deposited along the deposition direction of the arrow shown in FIG. 3(c), a clean S--N interface is obtained. Therefore, by further forming a superconducting counter electrode thereon, a 5-N-5 Josephson junction is formed.
以下に本発明の実施例を示す。 Examples of the present invention are shown below.
（実施例１）
第１図に本発明の第１の実施例の断面の略図を示す。図
中、１は酸化物超伝導体膜、２は基板、３は対向電極、
４は膜側壁襞開面、５は常伝導層、６は５−Ｎ−８接合
である。まず、真空中で低温に冷却した酸化物超伝導体
膜１が成膜されている基板２を劈開する。このようにし
て得られた清浄な膜側壁臂開面４に、矢印の方向から常
伝導層５及び超伝導対向電極３を真空成膜することによ
り、図示のような５−Ｎ−３接合６が得られる。この場
合酸化物超伝導体には多くの種類のものが考えられるが
、もっとも化学的に不安定なＹ−Ｂａ−Ｃｕ−０のよう
な酸化物超伝導体でも、常伝導層５に金又は白金を使用
することにより安定したＳ−Ｎ界面が得られる。常伝導
層５の厚さを数ｎｍにすることにより、かなりの高温ま
でジョセフソン結合を保つことができる。また酸化物超
伝導体がエピタキシャル膜であれば、平坦な膜側壁臂開
面４が得られるので、さらに良質のジョセフソン接合が
できる。対向電極３には金属超伝導体はもちろんのこと
、酸化物超伝導体を使用することも可能である。(Example 1) FIG. 1 shows a schematic cross-sectional view of a first example of the present invention. In the figure, 1 is an oxide superconductor film, 2 is a substrate, 3 is a counter electrode,
4 is a membrane side wall fold opening, 5 is a normal conductive layer, and 6 is a 5-N-8 junction. First, the substrate 2 on which the oxide superconductor film 1 is formed, which has been cooled to a low temperature in a vacuum, is cleaved. By vacuum forming a normal conductive layer 5 and a superconducting counter electrode 3 from the direction of the arrow on the thus obtained clean membrane side wall opening surface 4, a 5-N-3 junction 6 as shown in the figure is formed. is obtained. In this case, there are many types of oxide superconductors, but even the most chemically unstable oxide superconductor such as Y-Ba-Cu-0 has gold or gold in the normal conducting layer 5. By using platinum, a stable S-N interface can be obtained. By setting the thickness of the normal conductive layer 5 to several nanometers, Josephson coupling can be maintained even at considerably high temperatures. Furthermore, if the oxide superconductor is an epitaxial film, a flat film side wall opening surface 4 can be obtained, so that a Josephson junction of even better quality can be obtained. For the counter electrode 3, not only a metal superconductor but also an oxide superconductor can be used.
（実施例２）
第２図に本発明の第２の実施例の断面略図を示す。本実
施例の構成及び製法はほぼ第１の実施例と同じである。(Example 2) FIG. 2 shows a schematic cross-sectional view of a second example of the present invention. The structure and manufacturing method of this embodiment are almost the same as those of the first embodiment.
本実施例では予め劈開前に絶縁膜７を酸化物超伝導体膜
１上に成膜しておく。このようなサンプルを低温真空環
境内で劈開し、得られた膜側壁臂開面１及び絶縁膜７上
に、矢印で示した方向より常伝導層５及び対向電極３を
成膜し５−Ｎ−５接合６を形成する。このようにすると
基板２の裏面に成膜する必要がなくなる。In this embodiment, an insulating film 7 is formed on the oxide superconductor film 1 in advance before cleavage. Such a sample is cleaved in a low-temperature vacuum environment, and a normal conductive layer 5 and a counter electrode 3 are formed on the obtained film side wall arm opening surface 1 and insulating film 7 in the direction shown by the arrow. -5 Form junction 6. In this way, there is no need to form a film on the back surface of the substrate 2.
以上説明したように本発明によれば、酸化物超伝導体を
少なくとも一方の電極に使用した清浄なＳ−Ｎ界面を持
つ良質な５−Ｎ−５接合を形成できる効果を有する。As explained above, according to the present invention, it is possible to form a high-quality 5-N-5 junction with a clean S-N interface using an oxide superconductor for at least one electrode.
第１図及び第２図はそれぞれ本発明の第１及び第２の実
施例の断面同一第３図（ａ）〜（ｃ）はＳ−Ｎ界面を得
る手順を示す図、第４図は従来例の断面図である。1 and 2 are the same cross-sections of the first and second embodiments of the present invention. FIG. 3 is an example cross-sectional view.
Claims (2)
常伝導層を介して前記酸化物超伝導体膜と前記常伝導層
上に作られた超伝導対向電極膜とをジョセフソン結合さ
せたことを特徴とするジョセフソン接合。(1) The oxide superconductor film and the superconducting counter electrode film formed on the normal conductive layer are connected via the normal conductive layer formed on the cleavage plane of the side wall of the oxide superconductor film. A Josephson junction characterized by a Josephson junction.
真空環境下において劈開し、得られた膜側壁劈開面上に
、前記低温真空環境下において常伝導層及び超伝導対向
電極膜を順次成膜することを特徴とするジョセフソン接
合の製造方法。(2) The oxide superconductor film formed on the substrate is cleaved in a low-temperature vacuum environment, and a normal conductive layer and a superconducting counter electrode are placed on the resulting film sidewall cleavage plane in the low-temperature vacuum environment. A method for manufacturing a Josephson junction characterized by sequentially forming films.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1028000A JPH02206183A (en) | 1989-02-06 | 1989-02-06 | Josephson junction and manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1028000A JPH02206183A (en) | 1989-02-06 | 1989-02-06 | Josephson junction and manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02206183A true JPH02206183A (en) | 1990-08-15 |
Family
ID=12236543
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1028000A Pending JPH02206183A (en) | 1989-02-06 | 1989-02-06 | Josephson junction and manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02206183A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9362439B2 (en) * | 2008-05-07 | 2016-06-07 | Silicon Genesis Corporation | Layer transfer of films utilizing controlled shear region |
-
1989
- 1989-02-06 JP JP1028000A patent/JPH02206183A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9362439B2 (en) * | 2008-05-07 | 2016-06-07 | Silicon Genesis Corporation | Layer transfer of films utilizing controlled shear region |
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