JPH0590655A - Josephson junction device - Google Patents
Josephson junction deviceInfo
- Publication number
- JPH0590655A JPH0590655A JP3251037A JP25103791A JPH0590655A JP H0590655 A JPH0590655 A JP H0590655A JP 3251037 A JP3251037 A JP 3251037A JP 25103791 A JP25103791 A JP 25103791A JP H0590655 A JPH0590655 A JP H0590655A
- Authority
- JP
- Japan
- Prior art keywords
- bridge
- critical current
- junction
- film
- water
- 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
- 239000010408 film Substances 0.000 claims abstract description 19
- 239000010409 thin film Substances 0.000 claims abstract description 7
- 239000002887 superconductor Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims 1
- 239000007788 liquid Substances 0.000 abstract description 13
- 229910052734 helium Inorganic materials 0.000 abstract description 11
- 239000001307 helium Substances 0.000 abstract description 11
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 abstract description 11
- 238000000034 method Methods 0.000 abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 5
- 238000010030 laminating Methods 0.000 abstract description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract 6
- 229910052681 coesite Inorganic materials 0.000 abstract 3
- 229910052906 cristobalite Inorganic materials 0.000 abstract 3
- 239000000377 silicon dioxide Substances 0.000 abstract 3
- 235000012239 silicon dioxide Nutrition 0.000 abstract 3
- 229910052682 stishovite Inorganic materials 0.000 abstract 3
- 229910052905 tridymite Inorganic materials 0.000 abstract 3
- 230000008021 deposition Effects 0.000 abstract 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 7
- 238000007740 vapor deposition Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 3
- 230000020169 heat generation Effects 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000007743 anodising Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 239000011147 inorganic material Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 241000238366 Cephalopoda Species 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical class [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】 本発明はジョセフソン接合素子
に関し、例えば微小磁場を計測するためのＳＱＵＩＤ
や、ミリ波検出器等、ジョセフソン接合効果を利用した
あらゆるデバイスに応用することができる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Josephson junction device, for example, a SQUID for measuring a minute magnetic field.
Also, it can be applied to any device using the Josephson junction effect, such as a millimeter wave detector.
【０００２】[0002]
【従来の技術】 ジョセフソン接合素子のうち、準平面
型の素子やマイクロブリッジ型の素子をはじめとする、
いわゆるウィークリンク型の構造を持つジョセフソン接
合素子では、素子作製後に接合臨界電流のトリミングが
可能であるという特徴がある。このような素子における
接合臨界電流の調整方法としては、従来、陽極酸化法を
用いて、ウィークリンク部の超電導体薄膜を部分的に酸
化させることにより、その部分の超電導性を奪い、その
臨界電流を低下させる方法が主として採用されている。2. Description of the Related Art Among Josephson junction devices, quasi-plane type devices and microbridge type devices,
The Josephson junction device having a so-called weak link type structure is characterized in that the junction critical current can be trimmed after the device is manufactured. As a method of adjusting the junction critical current in such an element, conventionally, by using the anodic oxidation method, by partially oxidizing the superconducting thin film of the weak link portion, the superconductivity of the portion is deprived, and the critical current The method of lowering is mainly adopted.
【０００３】[0003]
【発明が解決しようとする課題】 ところで、陽極酸化
法では、素子を処理液に浸漬した状態で酸化させるた
め、接合臨界電流の調整に当たっては、素子を液体ヘリ
ウム中に浸して動作温度にまで冷却した状態で、接合臨
界電流を測定する工程と、常温において処理液中に浸し
て陽極酸化を行う工程とを繰り返す必要があり、調整作
業時間に長時間を要するという問題がある。By the way, in the anodizing method, since the element is oxidized in a state of being immersed in the treatment liquid, when adjusting the critical junction current, the element is immersed in liquid helium and cooled to the operating temperature. In such a state, it is necessary to repeat the step of measuring the junction critical current and the step of immersing in the treatment liquid at room temperature to perform anodic oxidation, and there is a problem that the adjustment work time requires a long time.
【０００４】また、素子を液体ヘリウム温度と常温の間
を往復させること、つまり熱サイクルを繰り返すこと
は、素子全体の劣化を促進するという問題もある。本発
明の目的は、素子を動作温度に冷却したままの状態でそ
の接合臨界電流を調整することができる構造を持つジョ
セフソン接合素子を提供することにある。Further, reciprocating the element between the temperature of liquid helium and room temperature, that is, repeating the thermal cycle, has a problem of promoting deterioration of the entire element. It is an object of the present invention to provide a Josephson junction device having a structure capable of adjusting the junction critical current while keeping the device cooled to the operating temperature.
【０００５】[0005]
【課題を解決するための手段】 上記の目的を達成する
ため、本発明のジョセフソン接合素子は、ウィークリン
ク型の素子において、少なくともウィークリンクを形成
する超電導体薄膜の上に、吸水性もしくは吸湿性の多孔
質無機物膜を積層したことによって特徴付けられる。In order to achieve the above object, the Josephson junction element of the present invention is a weak link type element, and in a weak link type element, absorbs water or absorbs moisture at least on a superconductor thin film forming a weak link. Characterized by laminating porous porous inorganic membranes.
【０００６】[0006]
【作用】 素子を液体ヘリウム等の冷媒中に浸漬した状
態で、ウィークリンクにその臨界電流値を越える電流を
通電すると、その部分は常電導状態となって抵抗が生
じ、発熱する。この発熱によりウィークリンクの上の吸
水性または吸湿性の多孔質無機物膜から水分が放出さ
れ、この水分によりウィークリンクを形成する超電導体
薄膜の一部が酸化されてその部分の超電導性が奪われ、
その結果としてウィークリンクの臨界電流が低下し、所
期の目的を達成できる。When an element is immersed in a coolant such as liquid helium and a current exceeding a critical current value is applied to the weak link, that portion becomes a normal conducting state and resistance is generated to generate heat. Due to this heat generation, moisture is released from the water-absorbing or hygroscopic porous inorganic film on the weak link, and this moisture oxidizes a part of the superconductor thin film forming the weak link, depriving the superconductivity of the part. ,
As a result, the critical current of the weak link decreases, and the intended purpose can be achieved.
【０００７】[0007]
【実施例】 図１は本発明を準平面型のジョセフソン接
合素子に適用した場合の実施例の構造を示す模式的斜視
図である。基板１上にNb製の下部電極２が形成されてい
るとともに、この下部電極２の一端部の表面には、Nb2O
5 等の絶縁膜３を介してNb製の上部電極４の一部が積層
形成されている。この下部電極２と上部電極４とは、こ
れら双方の表面に跨がって形成された同じくNb製のブリ
ッジ５によって互いにウィークに接合され、ここにジョ
セフソン接合部が形成されている。EXAMPLE FIG. 1 is a schematic perspective view showing the structure of an example in which the present invention is applied to a quasi-plane type Josephson junction element. A lower electrode 2 made of Nb is formed on the substrate 1, and Nb 2 O is formed on the surface of one end of the lower electrode 2.
A part of the upper electrode 4 made of Nb is laminated on the insulating film 3 such as 5 . The lower electrode 2 and the upper electrode 4 are weakly joined to each other by a bridge 5 also made of Nb formed over both surfaces thereof, and a Josephson junction is formed here.
【０００８】そして、ブリッジ５の表面には、SiO2蒸着
膜６が形成されている。このSiO2蒸着膜６は、蒸着条件
を調整することにより、多孔質膜となっている。以上の
構造の素子の接合臨界電流を調整するには、まず、素子
を大気中にしばらく放置するか、あるいは高湿度雰囲気
中に短時間放置する。これにより、SiO2蒸着膜６内には
水分が吸着する。A SiO 2 vapor deposition film 6 is formed on the surface of the bridge 5. The SiO 2 vapor deposition film 6 is a porous film by adjusting the vapor deposition conditions. In order to adjust the junction critical current of the element having the above structure, first, the element is left in the atmosphere for a while or left in a high humidity atmosphere for a short time. As a result, moisture is adsorbed in the SiO 2 vapor deposition film 6.
【０００９】次に、この素子を液体ヘリウム中に浸すと
ともに、４端子法に基づく臨界電流値の測定を行うため
に必要な配線を施しておく。その状態で、ブリッジ５に
その臨界電流値を越える電流を流す。これにより、ブリ
ッジ５は常電導状態となって発熱することになるが、こ
の発熱によりSiO2蒸着膜６から水分が放出され、その水
分がブリッジ５の表面に触れてその部分を酸化させる。
この発熱状態を適当な時間継続させた後には、酸化が適
当に進行し、ブリッジ５の臨界電流値が低下する。Next, this element is immersed in liquid helium, and wiring necessary for measuring the critical current value based on the 4-terminal method is provided. In that state, a current exceeding the critical current value is passed through the bridge 5. As a result, the bridge 5 is in a normal conducting state and generates heat, but due to this heat generation, moisture is released from the SiO 2 vapor deposition film 6, and the moisture comes into contact with the surface of the bridge 5 and oxidizes that portion.
After continuing this exothermic state for an appropriate period of time, oxidation proceeds appropriately and the critical current value of the bridge 5 decreases.
【００１０】その後、素子の接合臨界電流値を４端子法
によってモニタし、その値が所望値よりも大きい場合に
は、再度上述の通電を行う。以上の工程を繰り返すこと
により、素子を液体ヘリウムに浸したままの状態でその
接合臨界電流値を所望値に調整することができる。な
お、液体ヘリウム中で素子を発熱させる関係上、素子へ
の通電は、直流電流等を用いるよりも、パルス電流等と
して、短時間のうちに急激に昇温させる方法を繰り返す
ことが望ましい。After that, the junction critical current value of the element is monitored by the four-terminal method, and when the value is larger than a desired value, the above-mentioned energization is performed again. By repeating the above steps, the junction critical current value can be adjusted to a desired value while the element is immersed in liquid helium. In order to heat the element in liquid helium, it is preferable to repeat the method of rapidly heating the element in the short time as pulse current or the like rather than using direct current or the like.
【００１１】ここで、SiO2蒸着膜６等の多孔質無機物膜
は、ブリッジ５と液体ヘリウムとの間の断熱材としても
作用し、ブリッジ５の発熱が液体ヘリウムに一挙に伝わ
ることが防止される。本発明において使用可能な多孔質
無機物としては、上記のようなSiO2のほか、例えば他の
シリコン酸化物やAl2O3 等、殆どの多孔質セラミックを
使用することができる。Here, the porous inorganic material film such as the SiO 2 vapor deposition film 6 also acts as a heat insulating material between the bridge 5 and the liquid helium, and the heat of the bridge 5 is prevented from being transmitted to the liquid helium all at once. It As the porous inorganic material that can be used in the present invention, in addition to SiO 2 as described above, most porous ceramics such as other silicon oxides and Al 2 O 3 can be used.
【００１２】また、このような多孔質酸化膜は、上記の
実施例のようにブリッジの上方のみに形成することが望
ましいが、素子の表面一様に形成してもよく、この場合
には電極部分も酸化されることになるが、接合臨界電流
値と電極部分の臨界電流値とはそのオーダーが違うか
ら、多少の臨界電流値の低下は殆ど影響がない。更に、
本発明は以上のような準平面型のジョセフソン接合素子
に限らず、マイクロブリッジ型等の、いわゆるウィーク
リンク型（弱接合型）のジョセフソン接合素子に等しく
適用し得ることは言うまでもない。It is desirable that such a porous oxide film is formed only above the bridge as in the above-mentioned embodiment, but it may be formed evenly on the surface of the element. Although the part is also oxidized, since the order of the critical current value of the junction and the critical current value of the electrode part is different, a slight decrease in the critical current value has almost no effect. Furthermore,
It goes without saying that the present invention is not limited to the quasi-planar type Josephson junction element as described above, but is equally applicable to a so-called weak link type (weak junction type) Josephson junction element such as a microbridge type.
【００１３】[0013]
【発明の効果】 以上説明したように、本発明によれ
ば、ウィークリンクの上に吸水性または吸湿性の多孔質
無機物膜を形成しているので、素子を液体ヘリウムに浸
漬した状態でウィークリンクに臨界電流を越える電流を
流すことによって、その発熱により多孔質無機物膜から
水分を放出させてウィークリンクの一部を酸化させるこ
とが可能となり、素子を常温に戻すことなく液体ヘリウ
ムに漬けたままでその臨界電流値の調整を行うことがで
きる。その結果、従来の陽極酸化法による調整に比し
て、その所要時間を大幅に短縮することができるととも
に、熱サイクルにより素子が劣化することを防止でき
る。As described above, according to the present invention, since the water-absorbing or hygroscopic porous inorganic film is formed on the weak link, the weak link is immersed in the liquid helium. When a current exceeding the critical current is applied to the device, it is possible to release water from the porous inorganic film and oxidize a part of the weak link due to the heat generation, and the device remains immersed in liquid helium without returning to room temperature. The critical current value can be adjusted. As a result, compared with the conventional adjustment by the anodizing method, the required time can be significantly shortened and the element can be prevented from deteriorating due to the thermal cycle.
【図１】 本発明を準平面型ジョセフソン接合素子に適
用した実施例の構造を示す模式的斜視図FIG. 1 is a schematic perspective view showing the structure of an embodiment in which the present invention is applied to a quasi-planar Josephson junction device.
１・・・・基板 ２・・・・下部電極 ３・・・・絶縁膜 ４・・・・上部電極 ５・・・・ブリッジ ６・・・・SiO2蒸着膜1 ... substrate 2 ... lower electrode 3 ... insulating film 4 ... upper electrode 5 ... bridge 6 ... SiO 2 vapor deposition film
Claims (1)
体薄膜製のウィークリンクにより互いに接合されてる素
子において、少なくとも上記ウィークリンクを形成する
超電導体薄膜の上に、吸水性もしくは吸湿性の多孔質無
機物膜が積層されていることを特徴とするジョセフソン
接合素子。1. An element in which two electrodes made of a superconductor thin film are joined to each other by a weak link made of a superconductor thin film, and at least on the superconductor thin film forming the weak link, a water-absorbing or hygroscopic material is formed. A Josephson junction device characterized in that a porous inorganic film is laminated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3251037A JPH0590655A (en) | 1991-09-30 | 1991-09-30 | Josephson junction device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3251037A JPH0590655A (en) | 1991-09-30 | 1991-09-30 | Josephson junction device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0590655A true JPH0590655A (en) | 1993-04-09 |
Family
ID=17216679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3251037A Pending JPH0590655A (en) | 1991-09-30 | 1991-09-30 | Josephson junction device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0590655A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5821556A (en) * | 1994-03-25 | 1998-10-13 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Superconductive junction |
-
1991
- 1991-09-30 JP JP3251037A patent/JPH0590655A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5821556A (en) * | 1994-03-25 | 1998-10-13 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Superconductive junction |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5214744B2 (en) | Superconducting joining method of 2 generation high temperature superconducting wire using heat treatment under reduced oxygen partial pressure | |
| KR100964354B1 (en) | Method of joining YBCO-CC superconducting wire by the melting diffusion of two superconductor layers facing each other | |
| US4891355A (en) | Method for producing superconducting circuit | |
| JPH0590655A (en) | Josephson junction device | |
| JPS63239990A (en) | Superconducting transistor | |
| JPS63269585A (en) | Josephson junction device | |
| KR100964361B1 (en) | Method of joining YBCO-CC superconducting wire by the melting diffusion under the control of partial oxygen pressure | |
| JP2001091611A (en) | High magnetic field resolution fluxmeter | |
| JPS6411378A (en) | Formation of josephson element | |
| JPS63239740A (en) | Manufacture for superconductive compound thin film | |
| JPH05243625A (en) | Method of control critical current of josephson device | |
| JPS637675A (en) | Manufacture of superconducting device | |
| JP2748522B2 (en) | Method for producing high-temperature superconducting thin film | |
| JP2540185B2 (en) | Semiconductor device | |
| JPH01214178A (en) | Manufacture of josephson junction | |
| JPS57126185A (en) | Manufacture of josephson element | |
| JP2599500B2 (en) | Superconducting element and fabrication method | |
| JPH04302182A (en) | Junction critical current adjusting method for josephson junction element | |
| JPH0555649A (en) | Manufacture of superconducting electric field effect element | |
| JPS61265881A (en) | Thermal type superconductive switch | |
| JP2691065B2 (en) | Superconducting element and fabrication method | |
| JPS59218783A (en) | Thermal superconductive switch | |
| JP2731513B2 (en) | Superconducting element and method of manufacturing the same | |
| JPH065929A (en) | Josephson element | |
| JP4092393B2 (en) | High temperature superconducting Josephson junction forming method and high temperature superconducting Josephson device comprising Josephson junction formed thereby |