JPH0278282A - Josephson element - Google Patents
Josephson elementInfo
- Publication number
- JPH0278282A JPH0278282A JP63228423A JP22842388A JPH0278282A JP H0278282 A JPH0278282 A JP H0278282A JP 63228423 A JP63228423 A JP 63228423A JP 22842388 A JP22842388 A JP 22842388A JP H0278282 A JPH0278282 A JP H0278282A
- Authority
- JP
- Japan
- Prior art keywords
- superconducting
- barrier
- temperature
- superconducting electrode
- electrode material
- 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
- 239000000463 material Substances 0.000 claims abstract description 84
- 230000004888 barrier function Effects 0.000 claims abstract description 59
- 239000007772 electrode material Substances 0.000 claims abstract description 42
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 13
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 11
- 229910052772 Samarium Inorganic materials 0.000 claims abstract description 9
- 239000002887 superconductor Substances 0.000 claims description 11
- 229910052693 Europium Inorganic materials 0.000 claims description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 14
- 238000000034 method Methods 0.000 abstract description 13
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 8
- 238000009835 boiling Methods 0.000 abstract description 6
- 239000004020 conductor Substances 0.000 abstract 2
- 238000003475 lamination Methods 0.000 abstract 1
- 239000010408 film Substances 0.000 description 31
- 239000010949 copper Substances 0.000 description 7
- 229910052747 lanthanoid Inorganic materials 0.000 description 7
- 150000002602 lanthanoids Chemical class 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 241000238366 Cephalopoda Species 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000000059 patterning Methods 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 108091027981 Response element Proteins 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- NCEXYHBECQHGNR-UHFFFAOYSA-N chembl421 Chemical compound C1=C(O)C(C(=O)O)=CC(N=NC=2C=CC(=CC=2)S(=O)(=O)NC=2N=CC=CC=2)=C1 NCEXYHBECQHGNR-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical compound [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052727 yttrium Inorganic materials 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、高速な超伝導回路・高感度な磁場センサ等に
用いられるジョセフソン素子に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Josephson element used in high-speed superconducting circuits, highly sensitive magnetic field sensors, and the like.
従来、トンネル型ジョセフソン素子は、Ｐｂ。 Conventionally, tunnel type Josephson elements are made of Pb.
Ｎｂ、ＮｂＮ等の超伝導材料を用いて形成されていた。It was formed using superconducting materials such as Nb and NbN.
トンネルバリアとしては、超伝導材料の酸化物であるＰ
ｂ Ｏ，Ｎ ｂ ｔｏｘ等、または、超伝導材料とは
異なる物質、例えばＡｌ、、ｌ、Ｏ，、Ｍｇｏ、ＳｉＯ
□等が用いられてきた。このような材料構成のトンネル
型ジョセフソン素子においては、良好な特性が得られ、
超伝導メモリ、論理回路、磁場センサへの応用が進みつ
つある。As a tunnel barrier, P, which is an oxide of superconducting material, is used.
b O, N b tox, etc., or substances different from superconducting materials, such as Al, , 1, O, , Mgo, SiO
□ etc. have been used. A tunnel-type Josephson element with such a material composition has good characteristics,
Applications to superconducting memories, logic circuits, and magnetic field sensors are progressing.
しかし、このような材料においては超伝導臨界温度がＩ
ＯＫ以下と低く、極低温への冷却を必要とし、冷却に要
するコスト、設備は大きく、簡単に使用することは難し
い状態であった。However, in such materials, the superconducting critical temperature is I
The temperature was below OK, requiring cooling to an extremely low temperature, and the cost and equipment required for cooling were large, making it difficult to use easily.
近年、酸素欠損ペロブスカイト型構造のＹＢａ。In recent years, YBa with an oxygen-deficient perovskite structure has been developed.
Ｃｕ：ＩＯｙ等、超伝導臨界温度が液体窒素以上の超伝
導材料が開発され、安価な冷却手段により超伝導材料の
利用が可能になってきた。ＹＢａｚＣｕ３０ｙ等の酸化
物超伝導材料を用いたジョセフソン素子は特性制御の難
しい弱結合型での作製の報告はあるものの、制御性の良
好なトンネル型での作製の報告はない。Superconducting materials such as Cu:IOy, which have a superconducting critical temperature higher than that of liquid nitrogen, have been developed, and it has become possible to use superconducting materials with inexpensive cooling means. Although there are reports of fabrication of a Josephson element using an oxide superconducting material such as YBazCu30y in a weak coupling type whose characteristics are difficult to control, there is no report on fabrication of a tunnel type with good controllability.
超伝導臨界温度が７７Ｋを越える酸素欠損ペロブスカイ
ト型酸化物超伝導材料においては、従来バリア材料とし
て用いられていたＡ１．Ｍｇ、Ｓｉ等と超伝導材料との
反応が著しいため良好なバリアを形成することが難しい
こと、また、酸化物超伝導材料においては、従来のＰｂ
、Ｎｂ等の超伝導材料に比べ、コヒーレンス長ξが短く
、より薄＜、均一なバリアを必要とすることから、トン
ネル型ジョセフソン素子の作製は不可能であった。In oxygen-deficient perovskite-type oxide superconducting materials whose superconducting critical temperature exceeds 77 K, A1. It is difficult to form a good barrier because the reaction between Mg, Si, etc. and superconducting materials is significant, and in the case of oxide superconducting materials, conventional Pb
Compared to superconducting materials such as , Nb, etc., the coherence length ξ is shorter and a thinner and more uniform barrier is required, making it impossible to fabricate a tunnel-type Josephson device.
本発明はこのような点に鑑みてなされたものであり、そ
の目的とするところは、液体窒素沸点温度もしくは任意
の温度で動作するジョセフソン素子を実現することにあ
る。The present invention has been made in view of these points, and its purpose is to realize a Josephson element that operates at the boiling point temperature of liquid nitrogen or any temperature.
このような課題を解決するために本発明は、超伝導電極
材料とバリア材料と超伝導電極材料の３層構造からなる
ジョセフソン素子において、超伝導電極材料をＩ、ｎＸ
Ｂａ、、−、Ｃｕ３０ｙ構造とし、バリア材料を超伝導
電極材料と同一構造でかつ非超伝導体のＬｎｚＢａ３−
、Ｃｕ＊ｏｙとし、ＬｎをＬａ、Ｎｄ、Ｓｍ又はＥｕと
したものである。In order to solve these problems, the present invention has developed a Josephson device having a three-layer structure of a superconducting electrode material, a barrier material, and a superconducting electrode material.
The barrier material is LnzBa3-, which has the same structure as the superconducting electrode material and is a non-superconductor.
, Cu*oy, and Ln is La, Nd, Sm, or Eu.
また別発明として、超伝導電極材料とバリア材料と超伝
導電極材料の３層構造からなるジョセフソン素子におい
て、超伝導電極材料をＬｎｘＢａｆｆ−ｘＣｕ３Ｏｙ構
造とし、バリア材料を超伝導電極材料と同一構造でかつ
超伝導体のＬ ｎ ｚ Ｂ ａ ｆｆ−ｚ ＣＵ＝Ｏ，
とし、Ｚ＞Ｘ’とすることによりバリア材料の超伝導臨
界温度を超伝導電極材料の超伝導臨界温度より低くし、
ＬｎをＬａｓ Ｎｄ、Ｓｍ又はＥＵとしたとしたもので
ある。As another invention, in a Josephson element having a three-layer structure of superconducting electrode material, barrier material, and superconducting electrode material, the superconducting electrode material has a LnxBaff-xCu3Oy structure, and the barrier material has the same structure as the superconducting electrode material. and superconductor L nz B a ff-z CU=O,
By setting Z>X', the superconducting critical temperature of the barrier material is lower than the superconducting critical temperature of the superconducting electrode material,
Ln is Las Nd, Sm, or EU.
本発明によるジョセフソン素子は、液体窒素沸点温度も
しくは任意の温度で動作する。The Josephson device according to the invention operates at liquid nitrogen boiling temperature or any temperature.
本発明は、超伝導電極材料としてＬ ｎＸＢ ａ ｘ−
ｘＣ＋ｇＯ，（Ｌｎ＝Ｌａ、Ｎｄ、Ｓｍ、Ｅｕ）を用い
、バリア材料として超伝導材料とはＸの異なるＬｎｘＢ
ａ３−ｘｃ＋ｇｏｙ（Ｌｎ＝Ｌａ、Ｎｄｓ Ｓｍ。The present invention uses L nXB a x- as a superconducting electrode material.
xC+gO, (Ln=La, Nd, Sm, Eu), and LnxB, which has a different X from the superconducting material, is used as a barrier material.
a3-xc+goy (Ln=La, Nds Sm.
Ｅｕ）を用いることにより、超伝導電極材料とバリア材
料の間の反応がないこと、また、超伝導電極材料とバリ
ア材料をエピタキシャル成長により形成するため、高品
質なジョセフソン素子を形成することを可能としたもの
である。このような素子構造の素子が良好な特性を示す
理由を以下に示す。By using Eu), there is no reaction between the superconducting electrode material and barrier material, and since the superconducting electrode material and barrier material are formed by epitaxial growth, it is possible to form a high-quality Josephson device. That is. The reason why an element with such an element structure exhibits good characteristics will be explained below.
ＬｎｚＢａ２Ｃｕ３０．（Ｌｎ＝Ｙまたはランタノイド
系列の元素）はすべて約９０にの超伝導臨界温度を有す
る超伝導材料である。この中で、Ｌａ、Ｎｄ、Ｓｍ、Ｅ
ｕ等イオン半径の大きな元素を含有する材料においては
、ランタンイド元素の含有量とバリウム元素の含有量を
大きく変化させてもその結晶構造の変化は小さ（、かつ
、単一の相として存在する。このことは、文献ｒＬ１．
５Ｂａ１．５ｃｕｌｏｙ （Ｌ＝Ｌａ、Ｐｒ、Ｎｄ、Ｓ
ｍ、Ｅｕ、Ｇｄ、ＹおよびＹｂ）の結晶構造と電気的性
質２日本応用物理学会誌２６巻１１号Ｌ １８６５．鶴
見しげゆき、岩田恒和、田島ゆきみち、疋田真」（Ｃｒ
ｙｓｔａｌ ５ｔｒｕｃｔｕｒｅｓ ａｎｄ Ｅｌｅｃ
ｔｒｉｃａｌ Ｐｒｏｐｅｒｔｉ−ｅｓ ｏｆ Ｌ＋−
５Ｂａ＋−５ｃｕｉＯｙ（Ｌ＝Ｌａ＋Ｐｒ＋Ｎｄ＋’Ｓ
Ｔｌ＋ＥＬｌ＋Ｇｄ＋Ｙａｎｄ Ｙｂ）Ｊａｐａｎｅｓ
ｅ Ｊｏｕｒｎａｌ ｏｆ Ａｐｐｌｉｅｄ Ｐｈｙｓ
ｉｃｓｖｏｌ、２６ Ｎｏ、１１ Ｌ１８６５：Ｓｈｉ
ｇｅｙｕｋｉ Ｔｓｕｒｕｍｉ、Ｔｓｕｎｅｋａ−ｚｕ
Ｉｗａｔａ、Ｙｕｋｉｉｉｃｈｔ Ｔａｊｉｍａ ａ
ｎｄ Ｍａｋｏｔｏ Ｈｉｋｉｔａ）に記載されている
。格子定数は表１に示すようにほぼ等しく、その差は高
々１．５％である。このため、超伝導電極、バリアを上
記の材料で構成した場合、格子の整合性はよく、エピタ
キシャル成長をする。LnzBa2Cu30. (Ln=Y or elements of the lanthanide series) are all superconducting materials with superconducting critical temperatures of about 90°C. Among these, La, Nd, Sm, E
In materials containing elements with large ionic radii such as This is explained in the document rL1.
5Ba1.5culoy (L=La, Pr, Nd, S
Crystal structure and electrical properties of (m, Eu, Gd, Y and Yb) 2 Journal of the Japan Society of Applied Physics, Vol. 26, No. 11, L 1865. Shigeyuki Tsurumi, Tsunekazu Iwata, Yukimichi Tajima, Makoto Hikita” (Cr
ystal 5structures and Elec
trical Property-es of L+-
5Ba+-5cuiOy(L=La+Pr+Nd+'S
Tl+ELl+Gd+Yand Yb)Japanese
e Journal of Applied Phys.
icsvol, 26 No. 11 L1865:Shi
geyuki Tsurumi, Tsuneka-zu
Iwata, Yukiiiicht Tajima a
nd Makoto Hikita). The lattice constants are almost equal as shown in Table 1, and the difference is 1.5% at most. Therefore, when superconducting electrodes and barriers are made of the above materials, lattice matching is good and epitaxial growth is possible.
第１図はランタノイド元素含有量に対する超伝導臨界温
度を示したグラフである。ここで、超伝導臨界温度はＴ
ｃ ｍｉｄ （電気抵抗が超伝導開始温度における値の
１／２となる温度）で示す。FIG. 1 is a graph showing superconducting critical temperature with respect to lanthanide element content. Here, the superconducting critical temperature is T
It is expressed as c mid (temperature at which the electrical resistance becomes 1/2 of the value at the superconductivity initiation temperature).
第１図に示すように、ランタノイド元素の含有ｉｘに対
する超伝導臨界温度Ｔｃ ｍ１ｃｌはＸの増加に従い減
少し、Ｘの値が１．４より大きな領域では超伝導を示さ
なくなる。従って、Ｘの値を制御することによって、は
とんど同一の結晶構造を有したまま超伝導臨界温度Ｔｃ
ｍｉｄを任意に制御することが可能である。As shown in FIG. 1, the superconducting critical temperature Tc m1cl for the lanthanide element content ix decreases as X increases, and superconductivity is no longer exhibited in a region where the value of X is greater than 1.4. Therefore, by controlling the value of
It is possible to arbitrarily control mid.
発明者らはこのような特性に着目し、このような特性を
有する同一構成元素の材料をジョセフソン素子の電極材
料、バリア材料に用い、超伝導電極材料の上にバリア材
料をエピタキシャル成長させ、さらに超伝導電極材料を
エピタキシャル成長させることにより、超伝導電極材料
とバリア材料の界面を改善し、薄く、均一なバリアを形
成することにより、従来に比べ、特性の優れたジョセフ
ソン素子の作成を可能とした。The inventors focused on these characteristics, used materials with the same constituent elements that have these characteristics as the electrode material and barrier material of the Josephson element, epitaxially grew the barrier material on the superconducting electrode material, and further By epitaxially growing the superconducting electrode material, we can improve the interface between the superconducting electrode material and the barrier material and form a thin and uniform barrier, making it possible to create Josephson devices with superior properties compared to conventional methods. did.
超伝導膜、バリア膜の形成には、各構成元素の比を容易
に制御可能な形成法が望ましく、多元素同時蒸着法、多
元素同時スパッタ法などを用いる。For forming the superconducting film and the barrier film, it is desirable to use a formation method that allows the ratio of each constituent element to be easily controlled, such as a multi-element simultaneous vapor deposition method or a multi-element simultaneous sputtering method.
以下に示す実施例では多元素同時蒸着法による形成例を
示したが、エピタキシャル成長が可能な薄膜形成法であ
ればいずれの方法で形成してもよい。In the embodiments shown below, an example of formation using a multi-element simultaneous vapor deposition method is shown, but any thin film formation method that allows epitaxial growth may be used.
第２図は本発明によるジョセフソン素子の構造を示す構
造図である。同図において、１は第１の超伝導電極、２
はバリア膜、３は第２の超伝導電極である。FIG. 2 is a structural diagram showing the structure of a Josephson device according to the present invention. In the figure, 1 is the first superconducting electrode, 2
3 is a barrier film, and 3 is a second superconducting electrode.
次に、超伝導電極１，３とバリア膜２の材料を第１の実
施例として述べる。この実施例においては、第１．第２
の超伝導電極１，３の材料をＥｕ＋Ｂａｚｃｕ３０．
、バリア膜２の材料をＥｕ＋、５Ｂａ、、５ｃｕ＝ｏ。Next, materials for the superconducting electrodes 1 and 3 and the barrier film 2 will be described as a first example. In this embodiment, the first. Second
The material of the superconducting electrodes 1 and 3 is Eu+Bazcu30.
, the material of the barrier film 2 is Eu+, 5Ba, 5cu=o.
とする。超伝導電極１，３は超伝導臨界温度９０Ｋを有
する超伝導体、バリア膜２は非超伝導体である。shall be. The superconducting electrodes 1 and 3 are superconductors having a superconducting critical temperature of 90 K, and the barrier film 2 is a non-superconductor.
上記ジョセフソン素子の形成は次のような方法を用いる
。The Josephson element described above is formed using the following method.
まず、超伝導電極、バリア、超伝導電極の３層構造膜を
同一の真空チャンバ内で連続して形成する。基板はチタ
ン酸ストロンチウムの単結晶基板とし、基板面の結晶方
位が（１００）であるものを用いる。基板温度は５５０
℃とする。蒸着源はＥｕ、Ｂａ、Ｃｕの単一金属とし、
それぞれ単独に水晶振動子膜厚コントローラで蒸着スピ
ードを制御する。まず、Ｅｕ、Ｂａ、Ｃｕの組成比が１
：２：３となるように制御し、膜の堆積速度をほぼ毎分
２オングストロームとし、膜厚４０００オングストロー
ムまで堆積し、超伝導電極材料を形成する。その後、Ｅ
ｕ、Ｂａ、Ｃｕの組成比を１．５：１．５：３となるよ
うに制御し、膜厚が２０オングストロームのバリア膜材
料を形成する。この後、Ｅｕ、Ｂａ、Ｃｕの組成比が１
：２：３となるように制御し、膜の堆積速度をほぼ毎分
２オングストロームとし、前記と同一組成の超伝導電極
材料を３０００オングストローム形成し、超伝導電極、
バリア、超伝導電極の３層構造膜を得る。First, a three-layer structure film consisting of a superconducting electrode, a barrier, and a superconducting electrode is successively formed in the same vacuum chamber. The substrate used is a single crystal substrate of strontium titanate, and the crystal orientation of the substrate surface is (100). The substrate temperature is 550
℃. The evaporation source is a single metal of Eu, Ba, and Cu,
The deposition speed is controlled individually using a crystal oscillator film thickness controller. First, the composition ratio of Eu, Ba, and Cu is 1.
:2:3, the film deposition rate was approximately 2 angstroms per minute, and the film was deposited to a thickness of 4000 angstroms to form a superconducting electrode material. After that, E
The composition ratio of u, Ba, and Cu is controlled to be 1.5:1.5:3, and a barrier film material having a film thickness of 20 angstroms is formed. After this, the composition ratio of Eu, Ba, and Cu is 1.
:2:3, the film deposition rate was set to approximately 2 angstroms per minute, and 3000 angstroms of superconducting electrode material having the same composition as above was formed.
A three-layer structure film consisting of a barrier and a superconducting electrode is obtained.
蒸着時には酸素ガスを真空チャンバ内に流し、周波数１
３．５６ＭＨｚの電磁波を用いたｒｆ放電により酸素プ
ラズマを発生させ、膜中へ酸素の供給を行なった。得ら
れた膜がエピタキシャル成長していることは反射型電子
線回折装置により確認した。During deposition, oxygen gas is flowed into the vacuum chamber at a frequency of 1.
Oxygen plasma was generated by RF discharge using electromagnetic waves of 3.56 MHz, and oxygen was supplied into the film. It was confirmed by a reflection electron beam diffraction apparatus that the obtained film was epitaxially grown.
次に、形成された３層構造の膜を通常のフォトリソグラ
フィー技術、ドライエツチング技術を用いてパターン形
成し、測定に用いる２０μｍ×２０μｍの接合を形成し
た。Next, the formed three-layer film was patterned using conventional photolithography and dry etching techniques to form a 20 μm×20 μm junction used for measurement.
次に、同様に絶縁層および配線用超伝導電極を形成する
。絶縁層には真空蒸着による５ｉＯ１配線用超伝導電極
には上記に示した方法により形成したＥｕ＋ＢａｚＣｕ
：＋０．を用いる。Next, an insulating layer and a superconducting electrode for wiring are formed in the same manner. The insulating layer is vacuum evaporated, and the superconducting electrode for 5iO1 wiring is Eu+BazCu formed by the method shown above.
:+0. Use.
このように形成した素子は、一般のトンネル型ジョセフ
ソン素子の特性を示す。第３図は作製した素子の電流対
電圧特性を示す。縦軸が電流、横軸が電圧であり、測定
温度は７７にである。第３図（ａ）はＬｎ＝Ｅｕの場合
、第３図（ｂｌはＬｎ＝Ｎｄ、第３図（Ｃ）はＬｎ＝Ｓ
ｍ、第３図ｆｄ）はＬｎ＝Ｌａの場合である。このよう
な特性は超伝導デジタル回路等への応用に使用すること
ができる。The device formed in this manner exhibits the characteristics of a general tunnel-type Josephson device. FIG. 3 shows the current versus voltage characteristics of the fabricated device. The vertical axis is current, the horizontal axis is voltage, and the measured temperature is 77°C. Fig. 3(a) shows the case where Ln=Eu, Fig. 3(bl is Ln=Nd, Fig. 3(C) shows the case where Ln=S
m, Fig. 3 fd) is the case where Ln=La. Such characteristics can be used in applications such as superconducting digital circuits.
第３図に示すように、超伝導電極材料、バリア材料をＥ
ｕの代わりにＬａ、Ｎｄ、Ｓｍを含む材料で構成した場
合も同様な特性となる。このような良好な特性が得られ
ることは、薄＜、均一なバリアが形成されていることを
示している。As shown in Figure 3, superconducting electrode materials and barrier materials are
Similar characteristics can be obtained when a material containing La, Nd, and Sm is used instead of u. Obtaining such good properties indicates that a thin and uniform barrier is formed.
次に、本発明の第２の実施例について説明する。Next, a second embodiment of the present invention will be described.
第２図において、第１．第２の超伝導電極１，３の材料
をＥｕ１．＋ｓＢａ＋、５ｓＣｕ：＋Ｏｙ 、バリア膜
２の材料を［Ｅｕ＋、ｚｚｓ １．？７４ＣＬＩ３０
ｙとする。超伝導電極１゜ａ
３は超伝導臨界温度８０Ｋを有する超伝導体、バリア膜
２の材料は超伝導臨界温度７０に以下の超伝導体である
。第１の実施例と同様に超伝導電極１．３の材料とバリ
ア膜２の材料の格子定数の差は小さく、容易にエピタキ
シャル成長をする。膜の形成法、パターニング法は第１
の実施例と同様である。第１の超伝導電極１の材料の膜
厚は４０００オングストローム、バリア膜２の材料の膜
厚は１００オングストローム、第２の超伝導電極３の材
料の膜厚は３０００オングストロームである。In FIG. 2, 1. The material of the second superconducting electrodes 1 and 3 was Eu1. +sBa+, 5sCu: +Oy, the material of the barrier film 2 is [Eu+, zzs 1. ? 74CLI30
Let it be y. The superconducting electrode 1a3 is a superconductor having a superconducting critical temperature of 80 K, and the material of the barrier film 2 is a superconducting material having a superconducting critical temperature of 70 K or less. As in the first embodiment, the difference in lattice constant between the material of the superconducting electrode 1.3 and the material of the barrier film 2 is small, allowing easy epitaxial growth. Film formation method and patterning method are the first
This is similar to the embodiment. The thickness of the material for the first superconducting electrode 1 is 4000 angstroms, the thickness of the material for the barrier film 2 is 100 angstroms, and the thickness of the material for the second superconducting electrode 3 is 3000 angstroms.
第４図は作製した素子の電流対電圧特性を示す。FIG. 4 shows the current versus voltage characteristics of the fabricated device.
縦軸は電流、横軸は電圧であり、測定温度は７７にであ
る。第４図（ａ）はＬｎ＝Ｅｕの場合、第４図（ｂ）は
Ｌ ｎ ＝ Ｎ ｄ ％第４図（Ｃ）はＬｎ＝Ｓｍ、第
４図（ｄ）はＬｎ＝Ｌａの場合である。素子特性は第１
の実施例の場合とは異なり、ヒステリシスを持たない特
性となる。これは、バリア材料を７７Ｋにおける比抵抗
の小さな材料としたためである。このような特性は、ス
キュイド（ＳＱＵＩＤ）磁場センサ、電磁波検出素子酢
の応用に最適である。第４図に示すように、超伝導電極
材料、バリア材料をＥｕの代わりにＬａ、Ｎｄ、Ｓｍを
含む材料で構成した場合も同様な特性となる。The vertical axis is current, the horizontal axis is voltage, and the measured temperature is 77°C. Figure 4 (a) is for Ln = Eu, Figure 4 (b) is for L n = N d % Figure 4 (C) is for Ln = Sm, and Figure 4 (d) is for Ln = La. be. The element characteristics are the first
Unlike the case of the embodiment, the characteristic does not have hysteresis. This is because the barrier material is a material with low specific resistance at 77K. Such characteristics are optimal for application to SQUID magnetic field sensors and electromagnetic wave detection elements. As shown in FIG. 4, similar characteristics are obtained when the superconducting electrode material and barrier material are made of materials containing La, Nd, and Sm instead of Eu.
次に、本発明の第３の実施例について説明する。Next, a third embodiment of the present invention will be described.
素子の動作温度を任意に制御する例として、３０にで動
作する素子の構成例を示す。第２図において、第１．第
２の超伝導電極１．３の材料をＥＩＩ＋、３Ｂａｌ、
７ＣＬＩ３０ｙ ％バリア膜２の材料をＥｕ、 ｚＪａ
ｌ、 ｉ＋ｚＣｕ３０、とする。超伝導電極１，３は超
伝導臨界温度４、 ＯＫを存する超伝導体、バリア膜２
の材料は超伏ｉｔ＞＝昇温度２０に以下の超伝導体であ
る。第１の実施例と同様に超伝導電極材料とバリア膜材
料の格子定数の差は小さく、容易にエピタキシャル成長
をする。膜の形成法、パターニング法は第１の実施例と
同様である。第１の超伝導電極１の材料の膜厚は４００
０オングストローム、バリア膜２の材料の膜厚は１００
オングストローム、第２の超伝導電極３の材料の膜厚は
３０００オングストロームである。As an example of arbitrarily controlling the operating temperature of the element, a configuration example of an element operating at 30 is shown. In FIG. 2, 1. The materials of the second superconducting electrode 1.3 are EII+, 3Bal,
7CLI30y% Barrier film 2 material is Eu, zJa
l, i+zCu30. Superconducting electrodes 1 and 3 are superconductors with a superconducting critical temperature of 4 and OK, and barrier film 2
The material is a superconductor with a superconductivity>=temperature increase of 20 or less. Similar to the first embodiment, the difference in lattice constant between the superconducting electrode material and the barrier film material is small, making epitaxial growth easy. The film formation method and patterning method are the same as in the first embodiment. The film thickness of the material of the first superconducting electrode 1 is 400
0 angstrom, and the thickness of the barrier film 2 material is 100 angstroms.
The film thickness of the material of the second superconducting electrode 3 is 3000 angstroms.
第５図は第３の実施例で作製した素子の電流対電圧特性
を示す。縦軸は電流、横軸は電圧であり、測定温度は３
０にである。第５図（ａ）はＬｎ＝Ｅｕの場合、第５図
（ｂ）はＬｎ＝Ｎｄ、第５図（Ｃ）はＬｎ＝Ｓｍ、第５
図ｆｄｌはＬｎ＝Ｌａの場合である。素子特性は第２の
実施例の場合と同様に、ヒステリシスを持たない特性と
なる。これは、バリア材料を３０Ｋにおける比抵抗の小
さな材料としたためである。このような特性は、３０に
で動作させる電磁波検出素子等の応用に最適である。第
５図に示すように、超伝導電極材料、バリア材料をＥｕ
の代わりにＬａ、Ｎｄ、Ｓｍを含む材料で構成した場合
も同様な特性となる。FIG. 5 shows the current versus voltage characteristics of the device manufactured in the third example. The vertical axis is current, the horizontal axis is voltage, and the measured temperature is 3
It is at 0. Fig. 5(a) shows Ln=Eu, Fig. 5(b) shows Ln=Nd, Fig. 5(C) shows Ln=Sm, and Fig. 5(b) shows Ln=Sm.
Figure fdl shows the case where Ln=La. The device characteristics have no hysteresis, as in the second embodiment. This is because the barrier material is a material with low specific resistance at 30K. Such characteristics are optimal for applications such as electromagnetic wave detection elements operated at 30°C. As shown in Figure 5, the superconducting electrode material and barrier material are Eu
Similar characteristics can be obtained when a material containing La, Nd, and Sm is used instead.
次に、第４の実施例について説明する。第３の実施例で
は小型冷凍機で容易に実現可能な３０にでの動作を目標
としたため、超伝導電極材料の組成をＥｔｌ＋、Ｊａ＋
、ｔＣｕＪｙ 、バリア材料の組成をＥｕ、。Next, a fourth example will be described. In the third example, the composition of the superconducting electrode material was changed to Etl+, Ja+, since the target was operation at 30°C, which can be easily achieved with a small refrigerator.
, tCuJy, the composition of the barrier material is Eu.
３ＢＢａ（、ｂ□Ｃｕ３０ｙとしたが、超伝導材料、バ
リア材料の組成を、超伝導電極材料のＴｃ ｍｉｄが目
標とする動作温度より高く、バリア材料のＴｃ ｍｉｄ
が動作温度より低くなるような組成となるように選ぶこ
とにより、任意の動作温度の素子の形成が可能である。3BBa(,b□Cu30y), but the composition of the superconducting material and barrier material was set so that the Tc mid of the superconducting electrode material was higher than the target operating temperature, and the Tc mid of the barrier material was
By selecting a composition such that the temperature is lower than the operating temperature, it is possible to form a device with an arbitrary operating temperature.
表２に、様々な温度で動作する素子の例を示す。Table 2 shows examples of devices operating at various temperatures.
表２において、Ｔｃ ｏｎは超伝導開始温度、Ｔｃ ｍ
ｉｄは電気抵抗が超伝導開始温度における値の１／２と
なる温度、Ｔｃ ｅｎｄは電気抵抗がゼロとなる温度、
Ｔａは測定された動作温度、Ｓは超伝導電極材料、Ｂは
バリア材料である。作製法は第１の実施例と同じである
。ここに示すように、超伝導電極材料とバリア材料の超
伝導臨界温度の差が少ない場合には動作可能温度範囲が
狭いため、バリア材料としては超伝導臨界温度の低い材
料を用いることが望ましい。In Table 2, Tc on is the superconductivity onset temperature, Tc m
id is the temperature at which the electrical resistance becomes 1/2 of the value at the superconductivity starting temperature, Tc end is the temperature at which the electrical resistance becomes zero,
Ta is the measured operating temperature, S is the superconducting electrode material, and B is the barrier material. The manufacturing method is the same as the first example. As shown here, when the difference in superconducting critical temperature between the superconducting electrode material and the barrier material is small, the operable temperature range is narrow, so it is desirable to use a material with a low superconducting critical temperature as the barrier material.
この実施例で示すように、２種類以上のランタノイド元
素を含む材料においても同様な結果となることは明らか
であり、不純物としてＹ等イオン半径の小さなランタノ
イド元素が含有されても同様な結果となる。また、ラン
タンイド、バリウム、銅の組成比のずれも許容できる。As shown in this example, it is clear that similar results can be obtained with materials containing two or more types of lanthanide elements, and even if a lanthanide element with a small ionic radius such as Y is contained as an impurity, the same result will be obtained. . Furthermore, deviations in the composition ratios of lanthanide, barium, and copper are also acceptable.
一般に、ジョセフソン素子の電磁波照射により応答する
、つまりシャピロステップの出現する温度は超伝導電極
材料のＴｃ ｍｉｄ近傍であり、７７にで動作するジョ
セフソン素子を３０’にで動作させることは難しい。ま
た、ジョセフソン素子の応用は第２の実施例のように７
７にで手軽に使用するばかりでなく、動作温度を下げ、
熱による雑音を減少させ、より高感度に使用するという
場合も多い。このような場合には第３の実施例で示した
ような低い温度で動作するジョセフソン素子が有用であ
る。このように、本発明を用いることにより、同じ構造
、同じ作製法により動作温度を任意に変化させたジョセ
フソン素子を作製可能である。Generally, the temperature at which a Josephson element responds to electromagnetic irradiation, that is, the temperature at which a Shapiro step appears, is near Tc mid of the superconducting electrode material, and it is difficult to operate a Josephson element that operates at 77° at 30'. Furthermore, the application of the Josephson element is as shown in the second embodiment.
Not only is it easy to use, but it also lowers the operating temperature.
It is often used to reduce thermal noise and achieve higher sensitivity. In such a case, a Josephson element that operates at a low temperature as shown in the third embodiment is useful. As described above, by using the present invention, it is possible to manufacture a Josephson element with the same structure and the same manufacturing method in which the operating temperature is arbitrarily changed.
また、バリア材料として、同様な構造でかつ動作温度に
おける電気伝導度の異なる材料を使用することができる
ため、ヒステリシスの必要なデジタル回路への応用から
、ヒステリシスの不必要なスキュイド（ＳＱＵＩＤ）磁
場センサ、電磁波応答素子への応用まで幅広い領域でこ
の技術を適用できる。In addition, since it is possible to use materials with a similar structure but different electrical conductivity at the operating temperature as a barrier material, it is possible to use SQUID magnetic field sensors that do not require hysteresis, from applications to digital circuits that require hysteresis. This technology can be applied in a wide range of fields, including applications to electromagnetic wave response elements.
以上説明したように本発明は、超伝導電極材料をｌ、ｎ
、Ｂａ、−Ｘｃｕ３０ｙ構造とし、バリア材料を超伝導
電極材料と同一構造でかつ非超伝導体のＬｎ、Ｂ ａｓ
−２ｃｕ３０ｙとし、ＬｎをＬａ、Ｎｄ、Ｓｍ又はＥｕ
としたことにより、薄（、均一なバリア膜を形成できる
ので、液体窒素の沸点以上で動作する高品質なジョセフ
ソン素子を素子の特性を制御して形成できる効果がある
。As explained above, the present invention uses superconducting electrode materials l, n
, Ba, -Xcu30y structure, and the barrier material is Ln, Bas, which has the same structure as the superconducting electrode material and is a non-superconductor.
-2cu30y, Ln is La, Nd, Sm or Eu
By doing so, a thin (and uniform) barrier film can be formed, which has the effect of making it possible to form a high-quality Josephson device that operates above the boiling point of liquid nitrogen by controlling the characteristics of the device.
また、超伝導電極材料をＬ ｎ、Ｂ ａ ３−ｘＣｕ３
０ｙ構造とし、バリア材料を超伝導電極材料と同一構造
でかつ超伝導体のＬｎｚＢａ３−２Ｃｕ３０ｙとし、Ｚ
〉Ｘとすることによりバリア材料の超伝導臨界温度を超
伝導電極材料の超伝導臨界温度より低くし、Ｌｎをｌ、
ａ、Ｎｄ、Ｓｍ又はＥｕとしたことにより、Ｘと２に応
じて任意の動作温度を設定できるので、必要に応じて、
液体窒素沸点の温度だけでなく、それ以下の任意の温度
を動作点とするジョセフソン素子を形成できる効果があ
る。In addition, the superconducting electrode material is L n, B a 3-xCu3
0y structure, the barrier material is LnzBa3-2Cu30y which has the same structure as the superconducting electrode material and is a superconductor, and Z
〉X, the superconducting critical temperature of the barrier material is lower than the superconducting critical temperature of the superconducting electrode material, and Ln is set to l,
By using a, Nd, Sm, or Eu, any operating temperature can be set according to X and 2, so if necessary,
This has the effect of forming a Josephson element whose operating point is not only the temperature of the boiling point of liquid nitrogen but also any temperature below that temperature.
第１図はランタノイド元素含有量に対する超伝導臨界温
度を示すグラフ、第２図は本発明によるジョセフソン素
子の構造を示す構造図、第３図〜第５図は第１〜第３の
実施例で作製した素子の電流電圧特性を示すグラフであ
る。
１・・・第１の超伝導電極、２・・・バリア膜、３・・
・第２の超伝導電極。Fig. 1 is a graph showing the superconducting critical temperature with respect to the lanthanide element content, Fig. 2 is a structural diagram showing the structure of the Josephson element according to the present invention, and Figs. 3 to 5 are graphs showing the first to third embodiments. 3 is a graph showing the current-voltage characteristics of the device manufactured in 1... First superconducting electrode, 2... Barrier film, 3...
・Second superconducting electrode.
Claims (2)
３層構造からなるジョセフソン素子において、前記超伝
導電極材料をＬｎ＿ｘＢａ＿３＿−＿ｘＣｕ＿３Ｏ＿ｙ
構造とし、バリア材料を前記超伝導電極材料と同一構造
でかつ非超伝導体のＬｎ＿ｚＢａ＿３＿−＿ｚＣｕ＿３
Ｏ＿ｙとし、前記ＬｎをＬａ、Ｎｄ、Ｓｍ又はＥｕとし
たジョセフソン素子。(1) In a Josephson device consisting of a three-layer structure of a superconducting electrode material, a barrier material, and a superconducting electrode material, the superconducting electrode material is Ln_xBa_3_-_xCu_3O_y
structure, and the barrier material is Ln_zBa_3_-_zCu_3 which has the same structure as the superconducting electrode material and is a non-superconductor.
A Josephson element in which O_y is set and Ln is La, Nd, Sm, or Eu.
３層構造からなるジョセフソン素子において、前記超伝
導電極材料をＬｎ＿ｘＢａ＿３＿−＿ｘＣｕ＿３Ｏ＿ｙ
構造とし、バリア材料を前記超伝導電極材料と同一構造
でかつ超伝導体のＬｎ＿ｚＢａ＿３＿−＿ｚＣｕ＿３Ｏ
＿ｙとし、前記ｚを前記ｘより大きい値とすることによ
り前記バリア材料の超伝導臨界温度を前記超伝導電極材
料の超伝導臨界温度より低くし、前記ＬｎをＬａ、Ｎｄ
、Ｓｍ又はＥｕとしたジョセフソン素子。(2) In a Josephson device consisting of a three-layer structure of a superconducting electrode material, a barrier material, and a superconducting electrode material, the superconducting electrode material is Ln_xBa_3_-_xCu_3O_y
structure, and the barrier material has the same structure as the superconducting electrode material and is a superconductor Ln_zBa_3_-_zCu_3O.
_y, the superconducting critical temperature of the barrier material is made lower than the superconducting critical temperature of the superconducting electrode material by setting the z to a value larger than the x, and the Ln is set to La, Nd.
, Sm or Eu.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63228423A JPH0278282A (en) | 1988-09-14 | 1988-09-14 | Josephson element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63228423A JPH0278282A (en) | 1988-09-14 | 1988-09-14 | Josephson element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0278282A true JPH0278282A (en) | 1990-03-19 |
Family
ID=16876244
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63228423A Pending JPH0278282A (en) | 1988-09-14 | 1988-09-14 | Josephson element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0278282A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0294676A (en) * | 1988-09-30 | 1990-04-05 | Toshiba Corp | Superconducting device |
| JPH0570105A (en) * | 1991-09-17 | 1993-03-23 | Sumitomo Electric Ind Ltd | Oxide superconducting thin film |
| JPH0575171A (en) * | 1991-09-17 | 1993-03-26 | Sumitomo Electric Ind Ltd | Superconducting joint |
| JPH0585705A (en) * | 1991-09-26 | 1993-04-06 | Sumitomo Electric Ind Ltd | Oxide superconductive thin film |
| JPH05275758A (en) * | 1992-03-27 | 1993-10-22 | Toshiba Corp | Superconducting element |
-
1988
- 1988-09-14 JP JP63228423A patent/JPH0278282A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0294676A (en) * | 1988-09-30 | 1990-04-05 | Toshiba Corp | Superconducting device |
| JPH0570105A (en) * | 1991-09-17 | 1993-03-23 | Sumitomo Electric Ind Ltd | Oxide superconducting thin film |
| JPH0575171A (en) * | 1991-09-17 | 1993-03-26 | Sumitomo Electric Ind Ltd | Superconducting joint |
| JPH0585705A (en) * | 1991-09-26 | 1993-04-06 | Sumitomo Electric Ind Ltd | Oxide superconductive thin film |
| JPH05275758A (en) * | 1992-03-27 | 1993-10-22 | Toshiba Corp | Superconducting element |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2907832B2 (en) | Superconducting device and manufacturing method thereof | |
| Ramesh et al. | Ferroelectric bismuth titanate/superconductor (Y‐Ba‐Cu‐O) thin‐film heterostructures on silicon | |
| EP0390704B1 (en) | Tunnel junction type Josephson device and method for fabricating the same | |
| JP3278638B2 (en) | High-temperature superconducting Josephson junction and method of manufacturing the same | |
| JPH0278282A (en) | Josephson element | |
| EP0491496B1 (en) | Article comprising a superconductor/insulator layer structure, and method of making the article | |
| US5578554A (en) | Metal oxide material and method of manufacturing the same | |
| JP2979422B2 (en) | Method of manufacturing insulator and insulating thin film, and method of manufacturing superconducting thin film and superconducting thin film | |
| JP3186035B2 (en) | Laminated thin film for field effect element and field effect transistor using the laminated thin film | |
| JPS63225599A (en) | Preparation of oxide superconductive thin film | |
| JP2976427B2 (en) | Method of manufacturing Josephson device | |
| JP2899287B2 (en) | Josephson element | |
| JPH04334074A (en) | Superconducting device | |
| US5362709A (en) | Superconducting device | |
| JP2835203B2 (en) | Superconducting element manufacturing method | |
| JPH03275504A (en) | Oxide superconductor thin film and its production | |
| JP2555477B2 (en) | Superconducting thin film and manufacturing method thereof | |
| Eom et al. | Synthesis and characterization of superconducting thin films | |
| JP2809557B2 (en) | Copper oxide material | |
| JP2866476B2 (en) | Laminated superconductor and manufacturing method thereof | |
| JP2647251B2 (en) | Superconducting element and fabrication method | |
| JPH02264486A (en) | Superconductive film weakly coupled element | |
| JPH04288885A (en) | Tunnel-type josephson element | |
| JPH0244024A (en) | Production of thin oxide superconducting film | |
| Luo et al. | Preparation of ferroelectric Pb (Zr0. 53Ti0. 47) O3 thin film on YBa2Cu3O7–δ film by magnetron sputtering |