JPH02244682A - Superconductive element - Google Patents
Superconductive elementInfo
- Publication number
- JPH02244682A JPH02244682A JP1064131A JP6413189A JPH02244682A JP H02244682 A JPH02244682 A JP H02244682A JP 1064131 A JP1064131 A JP 1064131A JP 6413189 A JP6413189 A JP 6413189A JP H02244682 A JPH02244682 A JP H02244682A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- oxide superconductor
- insulating layer
- superconducting
- ionization energy
- 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.)
- Granted
Links
- 239000002887 superconductor Substances 0.000 claims abstract description 70
- 239000012212 insulator Substances 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims description 8
- 239000010408 film Substances 0.000 abstract description 17
- 230000004888 barrier function Effects 0.000 abstract description 9
- 238000000034 method Methods 0.000 abstract description 7
- 239000010409 thin film Substances 0.000 abstract description 7
- 230000007704 transition Effects 0.000 abstract description 5
- 239000003989 dielectric material Substances 0.000 abstract description 2
- 229910003097 YBa2Cu3O7−δ Inorganic materials 0.000 abstract 2
- 229910002370 SrTiO3 Inorganic materials 0.000 abstract 1
- 239000004065 semiconductor Substances 0.000 description 18
- 238000002347 injection Methods 0.000 description 8
- 239000007924 injection Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 239000000758 substrate Substances 0.000 description 6
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000000615 nonconductor Substances 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000005641 tunneling Effects 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 2
- 230000007547 defect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910014454 Ca-Cu Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000003113 dilution method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000001659 ion-beam spectroscopy Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 238000001451 molecular beam epitaxy Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000005268 plasma chemical vapour 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
- 230000003746 surface roughness Effects 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
［発明の目的］
（産業上の利用分野）
本発明は、酸化物超電導体を用いた超電導素子に関する
。Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a superconducting element using an oxide superconductor.
（従来の技術）
従来から、ある温度以下でその電気抵抗が零となる超電
導物質は数多く発見されており、それらを用いて超電導
導線や超電導電子デバイスなどを実現しようとする試み
が種々検討されてきている。また、最近、液体窒素の沸
点温度以上の転移温度を有する酸化物系の高温超電導体
、たとえばＹ−Ｂａ−Ｃｕ−０系で代表される酸素欠陥
を有する欠陥ペロブスカイト型の酸化物超電導体、さら
に臨界温度が高いＢ１−８「−Ｃａ−Ｃｕ−０系やＴ
Ｉ −Ｂａ−Ｃａ−Ｃｕ−０系の酸化物超電導体などが
種々発見され、これら高温超電導体を用いて高価な液体
ヘリウムを必要としない超電導素子を実現する試みが関
心を呼ぶに至っている。(Prior art) Many superconducting materials whose electrical resistance becomes zero below a certain temperature have been discovered, and various attempts have been made to use them to create superconducting wires, superconducting electronic devices, etc. ing. In addition, recently, oxide-based high-temperature superconductors having a transition temperature higher than the boiling point temperature of liquid nitrogen, such as defective perovskite-type oxide superconductors having oxygen defects represented by the Y-Ba-Cu-0 system, and B1-8 “-Ca-Cu-0 system and T
Various I-Ba-Ca-Cu-0-based oxide superconductors have been discovered, and attempts to use these high-temperature superconductors to realize superconducting elements that do not require expensive liquid helium are attracting attention.
超電導素子の多くは、ジョセフソン素子に代表されるよ
うに、超電導層／絶縁層／超電導層、あるいは超電導層
／半導体層／超電導層による接合を基本構造として含ん
でいる。ここで、上記超電導層／絶縁層／超電導層接合
における絶縁層は、充分なトンネル電流を得るために、
１０人〜５０人と言ったように充分に薄く形成しなけれ
ばならない。Many superconducting elements, as typified by Josephson elements, have a basic structure of a superconducting layer/insulating layer/superconducting layer or a superconducting layer/semiconductor layer/superconducting layer junction. Here, in order to obtain sufficient tunnel current, the insulating layer in the superconducting layer/insulating layer/superconducting layer junction is
It must be formed sufficiently thin, such as 10 to 50 people.
しかし、酸化物超電導体を利用して上記３層構造の接合
を形成しようとする場合、従来の合金系超電導体のよう
に金属薄膜を酸化することによって形成される酸化膜を
絶縁層とし、て利用することができず、また通常の絶縁
体を薄膜形成しようとする場合には、酸化物超電導体層
自体の表面平滑性を充分に向上させることが困難である
ために、。However, when attempting to form a junction with the above three-layer structure using an oxide superconductor, an oxide film formed by oxidizing a metal thin film is used as an insulating layer, as in conventional alloy-based superconductors. This is because it is difficult to sufficiently improve the surface smoothness of the oxide superconductor layer itself when attempting to form a thin film of an ordinary insulator.
表面粗さの大きい酸化物超電導体層上に充分に薄い絶縁
層を均一にかつ再現性よく形成することは非常に困難で
あった。It has been extremely difficult to uniformly and reproducibly form a sufficiently thin insulating layer on an oxide superconductor layer with large surface roughness.
一方、上記３層構造のトンネル接合に代えて、点接触型
やスリット型の接合方式による超電導素子も検討されて
いるが、将来超電導索子による集積回路などを］」指す
上では、上記３層構造の接合が不可欠である。On the other hand, instead of the three-layer tunnel junction described above, superconducting elements using point-contact or slit-type junctions are also being considered, but in the future integrated circuits using superconducting cables, etc. Structural bonding is essential.
（発明が解決しようとする課題）
上述したように、臨界温度の高い酸化物超電導体を用い
て良好な接合特性を示す超電導層／絶縁層／超電導層の
接合を構成する上で、酸化物超電導体層上に充分なトン
ネル電流を得ることが可能な絶縁層を再現性よく形成す
ることが必須条件であるが、現状の薄膜形成技術では、
酸化物超電導体層上に充分に薄い絶縁層を均一にかつ再
現性よく形成することは非常に困難を極めている。(Problems to be Solved by the Invention) As described above, in configuring a bond between a superconducting layer/insulating layer/superconducting layer that exhibits good bonding characteristics using an oxide superconductor with a high critical temperature, it is necessary to It is essential to form an insulating layer that can obtain sufficient tunneling current on the body layer with good reproducibility, but with the current thin film formation technology,
It is extremely difficult to uniformly and reproducibly form a sufficiently thin insulating layer on an oxide superconductor layer.
このように、良好な接合特性を示しか・つ再現性に優れ
た酸化物超電導体と絶縁体とによるトンネル接合は、今
だ得られていないのが現状である。As described above, at present, a tunnel junction between an oxide superconductor and an insulator that exhibits good junction characteristics and excellent reproducibility has not yet been obtained.
これは、準粒子注入型３端子素子などにおける超電導層
／絶縁層／半導体層によるトンネル接合においても同様
である。そして、酸化物超電導体を用いて具体的な超電
導素子を実現する上で、酸化物超電導体層上に絶縁層を
介在させることによって形成されるトンネル接合の接合
特性や再現性を向上させることが強く望まれている。This also applies to tunnel junctions formed by superconducting layers/insulating layers/semiconductor layers in quasi-particle injection type three-terminal devices and the like. In realizing specific superconducting elements using oxide superconductors, it is important to improve the junction characteristics and reproducibility of tunnel junctions formed by interposing an insulating layer on the oxide superconductor layer. Highly desired.
本発明は、このような課題に対処するためになされたも
ので、絶縁層の成形技術に拘らず、再現性に優れかつ良
好な接合特性が得られる、酸化物超電導体層上に絶縁層
を介在させることによって形成されるトンネル接合部を
有する超電導素子を提供することを目的としている。The present invention was made to address these issues, and it provides an insulating layer on an oxide superconductor layer that provides excellent reproducibility and good bonding properties regardless of the insulating layer forming technology. It is an object of the present invention to provide a superconducting element having a tunnel junction formed by interposition.
［発明の構成］
（課題を解決するための手段）
すなわち本発明は、酸化物超電導体層上に薄膜状の絶縁
層が介在されることによって形成されるトンネル接合部
を有する超電導素子において、前記絶縁層は、イオン化
エネルギーが５ｅＶ〜６．５ｅＶの範囲にあり、前記超
電導素子の動作温度において絶縁体として機能する物質
によって構成されていることを特徴としている。[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides a superconducting element having a tunnel junction formed by interposing a thin film-like insulating layer on an oxide superconductor layer. The insulating layer is characterized by being made of a material having an ionization energy in the range of 5 eV to 6.5 eV and functioning as an insulator at the operating temperature of the superconducting element.
酸化物超電導体としては多数のものが知られているが、
本発明においては希土類元素含有のペロブスカイト型構
造を有する酸化物超電導体や、Ｂ１．−８ｒ−Ｃａ−Ｃ
ｕ−０系酸化物超電導体、Ｔ Ｉ −Ｄａ−Ｃａ−Ｃｕ
−０系酸化物超電導体などが適用される。Many oxide superconductors are known, but
In the present invention, an oxide superconductor having a perovskite structure containing a rare earth element, B1. -8r-Ca-C
u-0 based oxide superconductor, T I -Da-Ca-Cu
-0 series oxide superconductor etc. are applied.
ここでいう希土類元素を含有しペロブスカイト型構造を
有する酸化物超電導体は、超電導状態を実現できるもの
であればよく、たとえばＬｒ１Ｍ Ｃｕ Ｏ系（Ｌ
ｎは Ｙ％ Ｌａ、、Ｓｅ、 Ｎｄ、、、 Ｓｍ。The oxide superconductor containing a rare earth element and having a perovskite structure may be one that can realize a superconducting state, for example, an Lr1M CuO system (Lr1M CuO system).
n is Y% La, Se, Nd, Sm.
２３７−δ
Ｅｕ、Ｇｄｓ Ｄｙ５ＨＯ％ Ｅｒｓ Ｔｍ、ＹＩ）、
Ｌｕなどの希土類元素から選ばれた少なくとも ｉｓの
元素を、ＨはＢａ、Ｓ「、Ｃａから選ばれた少なくとも
１種の元素を、δは酸素欠陥を表し通常１以下の数、
Ｃｕの一部はＴＩ、Ｖ 、Ｃｒ、Ｍｎｓ Ｆｅｓ ＣＯ
％旧、Ｚｎなどで置換可能。）の酸化物などが例示され
る。また、旧＝Ｓｒ−Ｃａ−Ｃｕ−〇系酸化物超電導体
は、化学式
％式％（１）
（式中、Ｂ１の一部はｐｂやｓｂなどで置換可能。）な
どで表されるものであり、Ｔ ｌ−Ｂａ−Ｃａ−Ｃｕ−
０系酸化物超電導体は、化学式
％式％）
などで表されるものである。237-δ Eu, Gds Dy5HO% Ers Tm, YI),
At least is element selected from rare earth elements such as Lu, H is at least one element selected from Ba, S, Ca, and δ represents an oxygen defect, usually a number of 1 or less,
Part of Cu is TI, V, Cr, Mns Fes CO
Can be replaced with % old, Zn, etc. ) are exemplified. In addition, the old = Sr-Ca-Cu-〇-based oxide superconductor is represented by the chemical formula % formula % (1) (in the formula, a part of B1 can be replaced with pb, sb, etc.). Yes, T l-Ba-Ca-Cu-
The 0-type oxide superconductor is represented by the chemical formula %.
また、本発明の超電導素子における絶縁層は、イオン化
エネルギーが５ｅＶ −６，５ｅｖの範囲にあり、超電
導素子の動作温度におい゛Ｃ絶縁体として機能する物質
によって構成される。たとえば、電気絶縁体または超電
導素子の動作温度において絶縁体として機能する（抵抗
値で１にΩ以上）半導体によって構成される。Further, the insulating layer in the superconducting element of the present invention is made of a substance having an ionization energy in the range of 5 eV - 6.5 ev and functioning as a C insulator at the operating temperature of the superconducting element. For example, it is made of an electrical insulator or a semiconductor that functions as an insulator at the operating temperature of the superconducting element (with a resistance value of 1 to Ω or more).
このような半導体材料としては、Ｇａ１−Ｘへｌｙ、Ａ
ｓ、ＧａＡｓ、ｘＰ 、などのｍ−ｖ族化合物半導体、
Ｚｎ５ｅｌ−、ＳｘなどのＩＮ−Ｖｌ族化合物半導体、
Ｓａ Ｔｅ ｓ Ｓ、−ｘＳｅｘなどの■族生
導体などが１−ｘ Ｘ
例示され、不純物のドーピング量を調節することによっ
てイオン化エネルギーを上記範囲内に制御することが可
能である。Such semiconductor materials include Ga1-X, A
m-v group compound semiconductors such as s, GaAs, xP,
IN-Vl group compound semiconductors such as Zn5el-, Sx,
Group II raw conductors such as SaTesS and -xSex are exemplified by 1-xX, and the ionization energy can be controlled within the above range by adjusting the doping amount of impurities.
ここで、絶縁層となる電気絶縁体または半導体のイオン
化エネルギーを５ｅＶ〜６．５ｅｖの範囲に限定したの
は、以下の理由による。Here, the reason why the ionization energy of the electric insulator or semiconductor serving as the insulating layer is limited to the range of 5 eV to 6.5 eV is as follows.
たとえば超電導層／絶縁層／超電導層によるトンネル障
壁の高さは、金属系超電導体を用いた場合には、金属の
仕事関数と絶縁体の電子親和力との差によってほぼ決定
されるが、酸化物超電導体を用いた場合には、酸化物超
電導体がｐ型の縮退半導体であるため、酸化物超電導体
のイオン化エネルギーと絶縁層のイオン化エネルギーと
の差によってほぼ決定され、この値をできるだけ小さく
することによって絶縁層の厚さを無視することが可能と
なる。そして、酸化物超電導体のイオン化エネルギーは
、従来の遷移金属酸化物の値から５ｅＶ −８，５ｅＶ
の範囲と推定される。したがって、絶縁層となる電気絶
縁体あるいは低温で絶縁体として振舞う半導体のイオン
化エネルギーの値を５ｅＶ〜６．５ｅＶの範囲とするこ
とによって、絶縁層の厚さを良好な膜形成が可能な程度
まで厚くしても、トンネル障壁の低い接合が得られ、充
分なトンネル電流を流すことが可能となる。For example, the height of the tunnel barrier formed by a superconducting layer/insulating layer/superconducting layer is determined approximately by the difference between the work function of the metal and the electron affinity of the insulator when using a metallic superconductor. When using a superconductor, since the oxide superconductor is a p-type degenerate semiconductor, it is determined almost by the difference between the ionization energy of the oxide superconductor and the ionization energy of the insulating layer, and this value should be made as small as possible. This makes it possible to ignore the thickness of the insulating layer. The ionization energy of the oxide superconductor is 5 eV -8, 5 eV from the value of the conventional transition metal oxide.
It is estimated that the range of Therefore, by setting the ionization energy value of the electrical insulator that becomes the insulating layer or the semiconductor that behaves as an insulator at low temperatures in the range of 5 eV to 6.5 eV, the thickness of the insulating layer can be reduced to a level that allows good film formation. Even if the thickness is increased, a junction with a low tunnel barrier can be obtained, and a sufficient tunnel current can flow.
また、この際の絶縁層構成材料のイオン化エネルギーは
、酸化物超電導体のイオン化エネルギーに対して± ０
．２ｅＶ程度に設定することが好ましい。In addition, the ionization energy of the insulating layer constituent material at this time is ± 0 with respect to the ionization energy of the oxide superconductor.
．． It is preferable to set it to about 2 eV.
本発明の超電導素子におけるトンネル接合は、たとえば
ジョセフソン素子、準粒子注入型３端子素子、５ＱＵＩ
Ｄ素子などにおける超電導層／絶縁層／超電導層による
ものや、準粒子注入型３端子素子における超電導層／絶
縁層／半導体層によるものなどである。The tunnel junction in the superconducting element of the present invention is, for example, a Josephson element, a quasi-particle injection type three-terminal element, a 5QUI
These include superconducting layer/insulating layer/superconducting layer in a D element, etc., and superconducting layer/insulating layer/semiconductor layer in a quasi-particle injection type three-terminal element.
本発明の超電導素子における超電導体層および絶縁層は
、マグネトロンスパッタ法、イオンビームスパッタ法、
クラスターイオンビーム法、分子線エピタキシ（ＭＢＥ
）法、プラズマＣＶＤ法などの各種薄膜形成法によって
得ることができる。また、超電導体層の厚さは、酸化物
超電導体が超電導特性を示す厚さ、すなわち概ね１００
０Å以上とすることが好ましく、絶縁層の厚さは上述し
たように各層の形成材料のイオン化エネルギーの差によ
って決定されるトンネル障壁の高さに依存し、トンネル
効果を阻害しない範囲内で良好な膜形成が可能な厚さ、
たとえば５０人〜１００人程度とすることが好ましい。The superconductor layer and the insulating layer in the superconducting element of the present invention can be formed by magnetron sputtering, ion beam sputtering,
Cluster ion beam method, molecular beam epitaxy (MBE)
) method, plasma CVD method, and various other thin film forming methods. The thickness of the superconductor layer is the thickness at which the oxide superconductor exhibits superconducting properties, that is, approximately 100
The thickness of the insulating layer is preferably 0 Å or more, and as mentioned above, the thickness of the insulating layer depends on the height of the tunnel barrier, which is determined by the difference in ionization energy of the materials forming each layer, and the thickness of the insulating layer is determined by the height of the tunnel barrier, which is determined by the difference in ionization energy of the materials forming each layer. Thickness that allows film formation,
For example, it is preferable to set the number to about 50 to 100 people.
（作 用）
たとえば超電導層／絶縁層／超電導層による接合の場合
、絶縁層の厚さが余り厚くなると、超電導体間の弱い接
合が得られなくなり、充分なトンネル電流が得られなく
なる。そこで、充分なトンネル電流を得るためには、ト
ンネル障壁の高さを充分に低くすることが重要である。(Function) For example, in the case of a superconducting layer/insulating layer/superconducting layer junction, if the thickness of the insulating layer becomes too thick, a weak junction between the superconductors cannot be obtained, and a sufficient tunneling current cannot be obtained. Therefore, in order to obtain a sufficient tunnel current, it is important to make the height of the tunnel barrier sufficiently low.
本発明においては、酸化物超電導体層上に絶縁層が介在
して形成されるトンネル障壁の高さが、酸化物超電導体
のイオン化エネルギーと絶縁層のイオン化エネルギーと
の差によってほぼ決定されることを利用し、絶縁層とな
る電気絶縁体あるいは低温で絶縁体として振舞う半導体
のイオン化エネルギーの値を５ｅＶ〜６゜５ｅＶと、酸
化物超電導体のイオン化エネルギーと同等な値に設定し
ているため、トンネル障壁の高さを極力低くすることが
でき、よって絶縁層の厚さを良好な膜形成が可能な程度
に多少厚くすることが可能となる。したがって、たとえ
ば酸化物超電導体層／絶縁層／酸化物超電導体層による
トンネル接合を極めて容易にかつ再現性よく得ることが
できる。In the present invention, the height of a tunnel barrier formed by interposing an insulating layer on an oxide superconductor layer is determined approximately by the difference between the ionization energy of the oxide superconductor and the ionization energy of the insulating layer. The ionization energy of the electrical insulator that serves as the insulating layer or the semiconductor that behaves as an insulator at low temperatures is set to 5 eV to 6.5 eV, which is equivalent to the ionization energy of the oxide superconductor. The height of the tunnel barrier can be made as low as possible, and therefore the thickness of the insulating layer can be made somewhat thicker to the extent that good film formation is possible. Therefore, for example, a tunnel junction using an oxide superconductor layer/insulating layer/oxide superconductor layer can be obtained extremely easily and with good reproducibility.
（実施例） 次に、この発明の実施例について説明する。(Example) Next, embodiments of the invention will be described.
第１図は、本発明を適用した一実施例のジョセフソン素
子を模式的に示す図である。チタン酸ストロンチウム（
５ｒＴｉ（ｈ ）基板１上には、厚さ約５０００人のＹ
Ｂａ２Ｃｕ３０．７．組成の第１の酸化物超電導体層２
（転移温度−９０Ｋ）がストライブ状に形成されている
。FIG. 1 is a diagram schematically showing a Josephson element according to an embodiment of the present invention. Strontium titanate (
On the 5rTi(h) substrate 1, a Y layer with a thickness of about 5000
Ba2Cu30.7. First oxide superconductor layer 2 of composition
(transition temperature -90K) is formed in a stripe shape.
この第１の酸化物超電導体層２上のほぼ中央部には、厚
さ約５０人の絶縁層３が形成されている。An insulating layer 3 having a thickness of approximately 50 mm is formed approximately at the center of the first oxide superconductor layer 2.
この絶縁層３はＧａＡｓ Ｐ からなるもので
あ０．４ ０．０
す、約５０にで電気絶縁体として機能し、またイオン化
エネルギーは約６ ｅ Ｖ−Ｑある。この絶縁層３上に
は、第１の酸化物超電導体層２と直交するように、厚さ
約５０００人のＹ１３ａ Ｃｕ Ｏ組成の第２２３
７−δ
の酸化物超電導体４（転移温度−７５Ｋ）がストライブ
状に形成されている。This insulating layer 3 is made of GaAs P and functions as an electrical insulator at about 50 Ω, and has an ionization energy of about 6 e V-Q. On this insulating layer 3, a 223rd layer of Y13a CuO composition with a thickness of about 5000 is deposited so as to be perpendicular to the first oxide superconductor layer 2.
A 7-δ oxide superconductor 4 (transition temperature -75K) is formed in a stripe shape.
そして、第１および第２の酸化物超電導体層２．４のそ
れぞれの両端部上に電流電圧端子となるＡｕ電極５．６
．７．８が形成されてジョセフソン素子が構成されてい
る。なお、第１および第２の酸化物超電導体層２．４の
形成材料であるＹ Ｂ ａ ２ＣＩＪ Ｏのイオン化
エネルギーは、ＵＰＳからの３７−δ
推定によると約６．３ｅＶである。Au electrodes 5.6 serving as current and voltage terminals are provided on both ends of each of the first and second oxide superconductor layers 2.4.
．． 7.8 are formed to constitute a Josephson element. Note that the ionization energy of Y B a 2CIJ O, which is the material for forming the first and second oxide superconductor layers 2.4, is about 6.3 eV according to 37-δ estimation from UPS.
このようなジョセフソン素子は、たとえば以下のように
して製造される。Such a Josephson element is manufactured, for example, as follows.
まず、５ｒＴＩ０３基板］上にレーザ蒸希法によってＹ
Ｂａ Ｃｕ Ｏ組成の酸化物超電導体膜を形２３７
−δ
成する。次に、この酸化物超電導体膜上に所定の幅でＭ
ＢＥ法によりＧａＡｓ Ｐ からなる半導体０
．４ Ｇ、８
膜を形成した後に、半導体膜が所定の長さだけ残存する
ように、ストライブ状にウェットエツチングなどによっ
て加工し、第１の酸化物超電導体層２と絶縁層３とを形
成する。First, Y was deposited on the 5rTI03 substrate using a laser dilution method.
The oxide superconductor film with Ba Cu O composition is shaped like 237
−δ is formed. Next, M is placed on this oxide superconductor film with a predetermined width.
Semiconductor 0 made of GaAs P by BE method
．． After forming the 4G, 8 film, the semiconductor film is processed into stripes by wet etching or the like so that a predetermined length remains, and the first oxide superconductor layer 2 and the insulating layer 3 are formed. do.
次いで、ストライブ状に形成された第１の酸化物超電導
体層２および絶縁層３上に、直交して第２の酸化物超電
導体層４が形成されるようにマスキングを施し、再びレ
ーザ蒸着法によってＹＢａ２Ｃｕ Ｏ組成の酸化物超
電導体膜を着膜させ、３７−δ
第２の酸化物超電導体層４を形成する。Next, masking is applied so that a second oxide superconductor layer 4 is formed perpendicularly on the first oxide superconductor layer 2 and the insulating layer 3 formed in a stripe shape, and laser deposition is performed again. An oxide superconductor film having a composition of YBa2CuO is deposited by a method to form a 37-δ second oxide superconductor layer 4.
この後、Ａｕ電極５．６．７．８を第１および第２の酸
化物超電導体層２．４の両端部に通常の蒸着法によって
形成し、ジョセフソン素子を得る。Thereafter, Au electrodes 5.6.7.8 are formed on both ends of the first and second oxide superconductor layers 2.4 by a conventional vapor deposition method to obtain a Josephson device.
このようにして作製した上記構成のジョセフソン素子の
電圧−電流特性を液体ヘリウム温度中で測定したところ
、第２図に示す結果が得られた。When the voltage-current characteristics of the Josephson device thus fabricated with the above structure were measured at liquid helium temperature, the results shown in FIG. 2 were obtained.
同図からも明らかなように、この実施例のジョセフソン
素子は、大きい超電導ギャップ（２Δ−１０ｍＶ）が観
測され、良好なジョセフソン接合が形成されていること
が確認された。As is clear from the figure, a large superconducting gap (2Δ-10 mV) was observed in the Josephson device of this example, and it was confirmed that a good Josephson junction was formed.
このように、この実施例のジョセフソン素子においては
、酸化物超電導体からなる第１および第２の酸化物超電
導体層２．４と絶縁層３とのイオン化エネルギーが近似
しているため、絶縁層３の厚さを５０人と比較的厚くし
ているのにも拘らず、充分なトンネル電流が得られ、結
果として大きい超電導ギャップが得られている。In this way, in the Josephson element of this example, since the ionization energies of the first and second oxide superconductor layers 2.4 made of oxide superconductors and the insulating layer 3 are similar, the insulation Although the thickness of the layer 3 is relatively thick at 50, a sufficient tunneling current is obtained, and as a result, a large superconducting gap is obtained.
次に、本発明の他の実施例について説明する。Next, other embodiments of the present invention will be described.
第３図は、本発明の超電導素子を準粒子注入型３端ｒ素
子に適用した実施例を示す図である。FIG. 3 is a diagram showing an embodiment in which the superconducting element of the present invention is applied to a quasi-particle injection type three-terminal r element.
同図において、１１はＧａＡｓからなる半導体基板であ
り、この半導体基板１１上には、この３端子素子の動作
温度で絶縁体として機能するＧ ａ Ａ ｓ ｏ 、
４Ｐ 膜１２を介して、ＹＢａ Ｃｕ Ｏ組成の
０．６ ２ ３ ７−δ第１の酸化
物超電導体層１３が形成されている。In the figure, 11 is a semiconductor substrate made of GaAs, and on this semiconductor substrate 11 are formed GaAso, which functions as an insulator at the operating temperature of this three-terminal element.
A first oxide superconductor layer 13 having a composition of YBa Cu O and having a composition of 0.6 2 3 7-δ is formed through the 4P film 12 .
この第１の酸化物超電導体層１３上には、同様にＧａ、
Ａｓ Ｐ 膜１４を介して、ＹＢａ２Ｃｕ３０
゜４０．６
０７−０組成の第２の酸化物超電導体層１５が形成され
、準粒子注入型３端子素子が構成されている。On this first oxide superconductor layer 13, Ga,
YBa2Cu30 through the As P film 14
A second oxide superconductor layer 15 having a composition of 0.40.6.07-0 is formed to constitute a quasi-particle injection type three-terminal device.
この準粒子注入型３端子素子においては、ＧａＡｓ
Ｐ 膜が第１の酸化物超電導体層１３０．４ ０
．８
上と第２の酸化物超電導体層１５とをトンネル接合する
絶縁層の他に、半導体基板１１から第１の酸化物超電導
体膜１３への準粒子注入のためのトンネル障壁としても
ＧａＡｓ Ｐ 膜が利用され０．４ ０．６
ており、それぞれにおいて良好なトンネル接合を形成し
ている。In this quasi-particle injection type three-terminal device, GaAs
The P film is the first oxide superconductor layer 130.4 0
．． 8. In addition to the insulating layer that tunnel-junctions the upper layer and the second oxide superconductor layer 15, GaAsP also serves as a tunnel barrier for quasiparticle injection from the semiconductor substrate 11 to the first oxide superconductor film 13. 0.4 and 0.6 films are used, forming good tunnel junctions in each.
［発明の効果］
以上説明したように本発明の超電導素子によれば、酸化
物超電導体層上に絶縁層を介在させることによって形成
されるトンネル接合における優れた接合特性を再現性よ
く得ることができる。したがって、酸化物超電導体を用
いたジョセフソン素子のような超電導素子の実現に大き
く貢献するものである。[Effects of the Invention] As explained above, according to the superconducting element of the present invention, it is possible to reproducibly obtain excellent junction characteristics in a tunnel junction formed by interposing an insulating layer on an oxide superconductor layer. can. Therefore, it will greatly contribute to the realization of superconducting devices such as Josephson devices using oxide superconductors.
第１図は本発明の一実施例のジョセフソン素子を示す斜
視図、第２図はその電流−電圧特性を示す図、第３図は
本発明の他の実施例の準粒子注入型３端子素子の構成を
模式的に示す断面図である。
２．１３・・・・・・第１の酸化物超電導体層、３・・
・・・・化合物半導体からなる絶縁層、４．１５・・・
・・・第２の酸化物超電導体層、
・・・・・・半導体基板、
１２、
４−＝−ＧａＡｓｏ、４
口、６
膜。FIG. 1 is a perspective view showing a Josephson device according to an embodiment of the present invention, FIG. 2 is a diagram showing its current-voltage characteristics, and FIG. 3 is a quasi-particle injection type 3-terminal diagram according to another embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the configuration of an element. 2.13...First oxide superconductor layer, 3...
...Insulating layer made of compound semiconductor, 4.15...
...Second oxide superconductor layer, ...Semiconductor substrate, 12, 4-=-GaAso, 4 ports, 6 film.
Claims (1)
によって形成されるトンネル接合部を有する超電導素子
において、 前記絶縁層は、イオン化エネルギーが５ｅＶ〜６．５ｅ
Ｖの範囲にあり、前記超電導素子の動作温度において絶
縁体として機能する物質によって構成されていることを
特徴とする超電導素子。[Scope of Claims] A superconducting element having a tunnel junction formed by interposing a thin insulating layer on an oxide superconductor layer, wherein the insulating layer has an ionization energy of 5 eV to 6.5 e.
A superconducting element, characterized in that the superconducting element is made of a material that is in the range of V and functions as an insulator at the operating temperature of the superconducting element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1064131A JP2746990B2 (en) | 1989-03-16 | 1989-03-16 | Superconducting element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1064131A JP2746990B2 (en) | 1989-03-16 | 1989-03-16 | Superconducting element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02244682A true JPH02244682A (en) | 1990-09-28 |
| JP2746990B2 JP2746990B2 (en) | 1998-05-06 |
Family
ID=13249217
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1064131A Expired - Fee Related JP2746990B2 (en) | 1989-03-16 | 1989-03-16 | Superconducting element |
Country Status (1)
| Country | Link |
|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0486404A2 (en) * | 1990-11-15 | 1992-05-20 | EASTMAN KODAK COMPANY (a New Jersey corporation) | Improved construction of high temperature Josephson junction device |
| EP1182712A2 (en) * | 2000-08-21 | 2002-02-27 | National Institute for Materials Science | Method for forming high temperature superconducting Josephson junction |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60142580A (en) * | 1983-12-28 | 1985-07-27 | インタ−ナショナル ビジネス マシ−ンズ コ−ポレ−ション | Transistor device |
| JPS63211688A (en) * | 1987-02-27 | 1988-09-02 | Hitachi Ltd | Superconducting transistor |
| JPS6446990A (en) * | 1987-08-17 | 1989-02-21 | Matsushita Electric Ind Co Ltd | Josephson element and manufacture thereof |
| JPS6451680A (en) * | 1987-08-22 | 1989-02-27 | Sumitomo Electric Industries | Oxide ceramics laminated layer structure and its manufacture |
| JPH01102973A (en) * | 1987-10-16 | 1989-04-20 | Hitachi Ltd | Photo-controlled superconducting device |
-
1989
- 1989-03-16 JP JP1064131A patent/JP2746990B2/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60142580A (en) * | 1983-12-28 | 1985-07-27 | インタ−ナショナル ビジネス マシ−ンズ コ−ポレ−ション | Transistor device |
| JPS63211688A (en) * | 1987-02-27 | 1988-09-02 | Hitachi Ltd | Superconducting transistor |
| JPS6446990A (en) * | 1987-08-17 | 1989-02-21 | Matsushita Electric Ind Co Ltd | Josephson element and manufacture thereof |
| JPS6451680A (en) * | 1987-08-22 | 1989-02-27 | Sumitomo Electric Industries | Oxide ceramics laminated layer structure and its manufacture |
| JPH01102973A (en) * | 1987-10-16 | 1989-04-20 | Hitachi Ltd | Photo-controlled superconducting device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0486404A2 (en) * | 1990-11-15 | 1992-05-20 | EASTMAN KODAK COMPANY (a New Jersey corporation) | Improved construction of high temperature Josephson junction device |
| EP1182712A2 (en) * | 2000-08-21 | 2002-02-27 | National Institute for Materials Science | Method for forming high temperature superconducting Josephson junction |
| EP1182712A3 (en) * | 2000-08-21 | 2004-10-06 | National Institute for Materials Science | Method for forming high temperature superconducting Josephson junction |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2746990B2 (en) | 1998-05-06 |
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