JPH0467692A - Superconducting element - Google Patents
Superconducting elementInfo
- Publication number
- JPH0467692A JPH0467692A JP2180973A JP18097390A JPH0467692A JP H0467692 A JPH0467692 A JP H0467692A JP 2180973 A JP2180973 A JP 2180973A JP 18097390 A JP18097390 A JP 18097390A JP H0467692 A JPH0467692 A JP H0467692A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- superconducting
- insulating film
- substrate
- film pattern
- 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
- 239000010409 thin film Substances 0.000 claims abstract description 53
- 239000010408 film Substances 0.000 claims abstract description 38
- 239000000758 substrate Substances 0.000 claims abstract description 25
- 239000013078 crystal Substances 0.000 abstract description 32
- 238000000034 method Methods 0.000 abstract description 11
- 239000000203 mixture Substances 0.000 abstract description 5
- 229910003097 YBa2Cu3O7−δ Inorganic materials 0.000 abstract 2
- 229910002561 K2NiF4 Inorganic materials 0.000 abstract 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 12
- 239000002887 superconductor Substances 0.000 description 9
- 238000001451 molecular beam epitaxy Methods 0.000 description 8
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 7
- 239000000395 magnesium oxide Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 229910052697 platinum Inorganic materials 0.000 description 6
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000000608 laser ablation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910000750 Niobium-germanium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000006114 decarboxylation reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910001195 gallium oxide Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000002294 plasma sputter deposition Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 238000013139 quantization Methods 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 230000007261 regionalization Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007740 vapor deposition Methods 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】
〔発明の目的〕
（産業上の利用分野）
本発明は超伝導素子にかかり、特にその絶縁膜の組成お
よび基板に関する。DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a superconducting device, and particularly to the composition of an insulating film and a substrate thereof.
（従来の技術）
超電導現象は、物質の示すさまざまな電磁気的性質の中
で最も特異な性質であるといわれており、完全導電性、
完全反磁性、磁束の量子化等、夫々の性質を利用し応用
面での今後の発展が期待されている。(Prior art) Superconductivity is said to be the most unique property among the various electromagnetic properties exhibited by substances, and is characterized by complete conductivity, complete conductivity,
Future developments in applications are expected by utilizing the respective properties such as perfect diamagnetism and quantization of magnetic flux.
このような超伝導現象を利用した電子デバイスとしては
、高速スイッチ、高感度検波素子、高感度磁束計をはし
め、広範囲の応用が期待されている。Electronic devices that utilize such superconducting phenomena are expected to have a wide range of applications, including high-speed switches, high-sensitivity detection elements, and high-sensitivity magnetometers.
従来の超伝導デバイスによく用いられる超伝導体として
は、例えば基板上にプラズマスパッター法により形成し
たＮｂ３Ｇｅ薄膜がある。この臨界温度は高々２３°に
であり、液体ヘリウム温度でしか使用てきないものであ
る。しかしながら、液体ヘリウムの使用は、液化・冷却
付帯設備の必要性に伴う冷却コストおよび技術的負担の
増大、更には、ヘリウム資源が極めて少ないことなどの
理由から、産業および民生分野での超電導体の実用化を
はばむ大きな問題となっていた。As a superconductor often used in conventional superconducting devices, there is, for example, a Nb3Ge thin film formed on a substrate by plasma sputtering. This critical temperature is at most 23° and can only be used at liquid helium temperatures. However, the use of liquid helium increases cooling costs and technical burden due to the need for liquefaction and cooling equipment, and furthermore, helium resources are extremely scarce. This was a major problem that hindered its practical application.
そこで、高臨界温度の超電導体を得るためにさまざまな
試みがなされており、特に、酸化物超伝導薄膜の最近の
研究はめざましく、超伝導臨界温度は７７°Ｋを上まわ
り、安価な液体窒素を冷媒として動作させることか可能
となった。Therefore, various attempts have been made to obtain superconductors with high critical temperatures.In particular, recent research on oxide superconducting thin films has been remarkable, and the superconducting critical temperature has exceeded 77°K. It has now become possible to operate it as a refrigerant.
このため、超伝導薄膜を用いた超伝導素子の研究が急速
に進められている。For this reason, research on superconducting elements using superconducting thin films is progressing rapidly.
典型的な超伝導素子として、Ｓ Ｉ Ｓ （Ｓｕｐｅｒ
ｃｏｎｄｕｃｔｏｒ Ｉｎ５ｕｌａｔｏｒ ５ｕｐｅｒ
ｃｏｎｄｕｃｔｏｒ ）構造と呼ばれる一トンネルバリ
アとしての絶縁膜を超伝導薄膜の間に挾み、ジョセフソ
ントンネル接合を形成した構造の素子がある。As a typical superconducting element, SIS (Super
conductor
There is an element called a conductor structure in which an insulating film serving as a tunnel barrier is sandwiched between superconducting thin films to form a Josephson tunnel junction.
このような超伝導素子においては、特性の良好な超伝導
薄膜を用いることの他に、絶縁膜の膜質が大きな問題と
なる。In such a superconducting element, in addition to using a superconducting thin film with good characteristics, the quality of the insulating film is a major issue.
従来、酸化物超伝導体を用いたジョセフソントンネル接
合には酸化マグネシウム（ＭｇＯ）や酸化アルミニウム
（Ａｊ！２０３ ）か用いられているが、これらはいず
れも酸化物超伝導体に対し格子定数のずれか約１０％あ
るいはそれ以上ある。Conventionally, magnesium oxide (MgO) or aluminum oxide (Aj!203) has been used for Josephson tunnel junctions using oxide superconductors, but these both have a lattice constant that is different from that of oxide superconductors. The difference is about 10% or more.
例えば、高臨界温度の酸化物超伝導体としては、ＬｎＢ
ａ Ｃｕ Ｏ（δ−０〜１．Ｌｎ：Ｙｂ、Ｅｒ、Ｙ
、Ｈｏ、Ｇｄ、Ｅｕ、Ｄｙ） 、ＢｉＳ ｒ−Ｃａ−Ｃ
ｕ−Ｑ系の酸化物薄膜、Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０系
の酸化物薄膜など、多くの酸化物が報告されている。For example, as a high critical temperature oxide superconductor, LnB
a Cu O(δ-0~1.Ln: Yb, Er, Y
, Ho, Gd, Eu, Dy), BiS r-Ca-C
Many oxides have been reported, such as u-Q-based oxide thin films and Tl-Ba-Ca-Cu-0-based oxide thin films.
そして、これらの酸化物の格子定数ａおよびｂは全て３
．７６〜３．９２人の範囲にある。また、座標系を４５
°回転させてみれば、Ｊ ２ ａおよびＪ２ｂを基本格
子ともみることかでき、この場合は格子定数ａおよびｂ
は５．３２〜５．５４人と表現されている。The lattice constants a and b of these oxides are all 3
．． It ranges from 76 to 3.92 people. Also, change the coordinate system to 45
If rotated by °, J2a and J2b can also be seen as fundamental lattices, and in this case, the lattice constants a and b
is expressed as 5.32 to 5.54 people.
これに対して、現在広く使用されている基板材料である
酸化マグネシウム（ＭｇＯ）は、ａ−４゜２０３人であ
り、格子定数の差は７〜１１％にも達し、良好なエピタ
キシャル成長膜を得るのは極めて困難であった。これは
、サファイア、ＹＳＺシリコン、砒化ガリウム、Ｌ １
Ｎｂｏ３．ＧＧＧについても同様であった。On the other hand, magnesium oxide (MgO), which is currently a widely used substrate material, has a -4°203 lattice constant difference of 7 to 11%, which allows for good epitaxial growth. It was extremely difficult. This is sapphire, YSZ silicon, gallium arsenide, L 1
Nbo3. The same was true for GGG.
このため、接合界面に格子歪か発生し、膜質が低下する
という問題があった。For this reason, there was a problem in that lattice strain occurred at the bonding interface and the film quality deteriorated.
絶縁膜を超伝導薄膜の間に挟む場合、超伝導薄膜上に絶
縁膜を堆積しさらにこの上に超伝導薄膜を形成しなけれ
ばならないため、両界面での格子歪か問題となる。When an insulating film is sandwiched between superconducting thin films, it is necessary to deposit the insulating film on top of the superconducting thin film and then form the superconducting thin film on top of this, which raises the issue of lattice strain at both interfaces.
超伝導素子で用いる絶縁膜は、２０ｎｍ程度以下と極め
て薄い膜であるため、この界面での歪に起因して、均一
でかつ絶縁効果の高い絶縁膜を得ることはできなかった
。Since the insulating film used in superconducting elements is extremely thin, about 20 nm or less, it has not been possible to obtain a uniform insulating film with a high insulating effect due to strain at this interface.
また、特定の条件で用いられるため、使用時において顕
在化してくる問題点も少なくなかった。Furthermore, since they are used under specific conditions, many problems arise during use.
このように、超伝導臨界電流（Ｊ Ｃ）を安定して大き
くすることができ、また超伝導臨界温度（Ｔｃ）の安定
な超伝導素子を得るためには優れた超伝導薄膜を優れた
エピタキシャル膜で形成する必要がある。In this way, in order to stably increase the superconducting critical current (J C) and obtain a superconducting device with a stable superconducting critical temperature (Tc), it is necessary to combine an excellent superconducting thin film with an excellent epitaxial layer. It must be formed from a membrane.
ところで、優れたエピタキシャル膜を生成するためには
、基板材料および絶縁膜としては次に示すような条件を
持つことが必要である。By the way, in order to produce an excellent epitaxial film, it is necessary for the substrate material and the insulating film to have the following conditions.
（１）薄膜結晶との格子整合が良いこと、（Ｉ［）エピ
タキシャル膜成長時における相互拡散による膜質の劣化
がないこと、
（ＩＩＩ）超伝導薄膜の成膜時に高温に加熱されるため
、高融点、少なくとも１０００℃以上の融点を有するこ
と、
（ＴＶ）結晶性の良好な単結晶が入手可能であること、
（Ｖ）電気的に絶縁性を有すること、
等である。(1) Good lattice matching with thin film crystals, (I) No deterioration of film quality due to interdiffusion during epitaxial film growth, (III) Superconducting thin films are heated to high temperatures during deposition, so (TV) A single crystal with good crystallinity is available; (V) It has electrical insulation properties.
このような条件を満たす絶縁膜は従来なく、このため、
良好な素子特性を得ることができないのみならず、不良
が発生し易いという問題があった。There is no existing insulating film that satisfies these conditions, and therefore,
There is a problem in that not only it is not possible to obtain good device characteristics, but also defects are likely to occur.
（発明が解決しようとする課題）
このように、超伝導素子においては絶縁膜の膜質が素子
の特性および歩留まりを大きく左右しており、優れた絶
縁膜の形成が望まれていた。(Problems to be Solved by the Invention) As described above, in a superconducting device, the quality of the insulating film greatly influences the characteristics and yield of the device, and it has been desired to form an excellent insulating film.
また、基板材料としても汎用性の高いものが望まれてい
た。Furthermore, a material with high versatility was desired as a substrate material.
本発明は、前記実情に鑑みてなされたもので、トンネル
接合用絶縁膜を改善し、特性が良好で信軸性の高い超伝
導素子を提供することを目的とする。The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to improve an insulating film for a tunnel junction and provide a superconducting element with good characteristics and high axial stability.
また、本発明は基板材料の制約なしに特性の良好な超伝
導装置を提供することを目的とする。Another object of the present invention is to provide a superconducting device with good characteristics without restrictions on substrate materials.
（課題を解決するための手段）
そこで本発明の第１では、第１の超伝導薄膜パターンと
第２の超伝導薄膜パターンとによって絶縁膜を挾んだト
ンネル接合素子において、この絶縁膜をＳｒＬａＧａＯ
４薄膜で構成している。(Means for Solving the Problems) Therefore, in the first aspect of the present invention, in a tunnel junction element in which an insulating film is sandwiched between a first superconducting thin film pattern and a second superconducting thin film pattern, this insulating film is made of SrLaGaO
It is composed of 4 thin films.
本発明の第２では、基板上に５ｒＬａＧａ０４薄膜を介
して超伝導素子を形成するようにしている。In the second aspect of the present invention, a superconducting element is formed on a substrate via a 5rLaGa04 thin film.
（作用）
この５ｒＬａＧａＣ）＋単結晶の格子定数は３゜８５人
で、酸化物超伝導体薄膜に対する格子定数の差は−１，
６〜２．６％と極めて小さい。また、結晶構造も極めて
近く、５ｒＬａＧａ０４単結晶の酸化物超伝導体薄膜と
の格子整合性は極めて優れており、前述した条件の全て
を具備している。(Function) The lattice constant of this 5rLaGaC)+ single crystal is 3°85, and the difference in lattice constant with respect to the oxide superconductor thin film is -1,
It is extremely small at 6-2.6%. In addition, the crystal structure is extremely similar, and the lattice matching with the 5rLaGa04 single crystal oxide superconductor thin film is extremely excellent, satisfying all of the above-mentioned conditions.
従って本発明の第１によればこれを絶縁膜として用いる
ことにより、格子歪の小さい良質の積層構造を得ること
かでき、良好な超伝導薄膜を得ることができる。Therefore, according to the first aspect of the present invention, by using this as an insulating film, a high-quality laminated structure with small lattice strain can be obtained, and a good superconducting thin film can be obtained.
本発明の第２によれば、基板上にＳｒＬａＧａＯ４薄膜
を介して超伝導素子を形成するようにしているため、い
かなる基板材料を用いても、超伝導薄膜との格子整合性
の良好な表面をえることかできるため、特性が良好で信
頼性の高い超伝導装置を得ることが可能となる。According to the second aspect of the present invention, since the superconducting element is formed on the substrate via the SrLaGaO4 thin film, no matter what substrate material is used, a surface with good lattice matching with the superconducting thin film can be obtained. Therefore, it is possible to obtain a superconducting device with good characteristics and high reliability.
（実施例）
以下、本発明の実施例について、図面を参照しつつ詳細
に説明する。(Example) Hereinafter, examples of the present invention will be described in detail with reference to the drawings.
実施例１
第１図は本発明の第１の実施例のジョセフソントンネル
素子を示す図である。Embodiment 1 FIG. 1 is a diagram showing a Josephson tunnel device according to a first embodiment of the present invention.
この素子は、組成が次式に示すようなに２ＮｉＦ４型の
結晶構造を有する、
Ｓ ｒ １− Ｌ ａ １− Ｇ
ａ ＋−ｒ Ｏ＜（−０，０５＜ｘ ＜０．０５．
−０．０５ ＜ｙ ＜０．０５．−０．０５ ＜ｚ ＜
０．０５ −０．２＜Ｗ ＜０．２ ）ストロンチウ
ム−ランタン−ガリウム系酸化物単結晶基板１上に、膜
厚２０〜２０００人のＹＢａ２Ｃｕ３０ 薄膜パタ
ーン２と、この基板と同７−δ
一組成の膜厚１０−２００人の５ｒＬａＧａ０４薄膜か
らなる絶縁膜パターン３とを当接せしめ、さらにこの絶
縁膜パターン３の上層に膜厚２０〜２０００人めＹＢａ
２ Ｃｕ３０ 薄膜パターン７−δ
４を形成したものである。This element has a 2NiF4 type crystal structure as shown in the following formula: S r 1- L a 1- G
a +-r O<(-0,05<x<0.05.
−0.05 <y <0.05. -0.05 <z <
0.05 -0.2<W<0.2) A YBa2Cu30 thin film pattern 2 with a film thickness of 20 to 2,000 people is placed on a strontium-lanthanum-gallium oxide single crystal substrate 1, and the same 7-δ An insulating film pattern 3 consisting of a thin film of 5rLaGa04 having a composition of 10 to 200 nm thick is brought into contact with the insulating film pattern 3, and an insulating film pattern 3 of 20 to 2000 m thick YBa is further formed on top of this insulating film pattern 3.
2Cu30 thin film pattern 7-δ4 is formed.
次にこのジョゼフソントンネル素子の製造方法について
説明する。Next, a method of manufacturing this Josephson tunnel element will be explained.
まず、出発原料として、Ｓ ｒｃＯ３，Ｌａ２０３、Ｇ
ａ２Ｏ３粉体を用い、これらをモル比がＳｒ ： Ｌ
ａ ： Ｇ ａ−０，９４： ０．９Ｂ： １．１０と
なるようにを混合し、１０００℃で仮焼し脱炭酸処理を
行った後、粉砕しプレス成形した。First, as starting materials, SrcO3, La203, G
Using a2O3 powder, the molar ratio of these is Sr:L
a: Ga-0,94: 0.9B: 1.10 were mixed, calcined at 1000°C to perform decarboxylation treatment, and then crushed and press-molded.
このようにして形成された成形体を大気中で１３００℃
で焼結することによりし、約１４５０ｇのＳｒＬａＧａ
Ｏ４焼結体を得た。The molded body thus formed was heated to 1300°C in the atmosphere.
Approximately 1450 g of SrLaGa
An O4 sintered body was obtained.
この焼結体を外形約８０ｍｍ、高さ約８０ ｍｍ、肉厚
２ＩＩＩＩＩ＋の白金るつほに入れ、高周波加熱によっ
て溶融せしめた。ここで白金るつほは、純白金ては使用
ごとの変形が著しいため、ジルコニア分散強化型白金る
つほを用いるようにすると良い。This sintered body was placed in a platinum melting box having an outer diameter of about 80 mm, a height of about 80 mm, and a wall thickness of 2III+, and was melted by high-frequency heating. Here, it is preferable to use a zirconia dispersion-strengthened platinum melt because pure platinum deforms significantly each time it is used.
このようにして融解せしめたＳｒＬａＧａＯ４焼結体か
ら、［１００］方位の種結晶を用いて、チョクラルスキ
ー引上げ法により、５ｒＬａＧａ０４単結晶を成長させ
た。From the SrLaGaO4 sintered body thus melted, a 5rLaGa04 single crystal was grown by the Czochralski pulling method using a [100] oriented seed crystal.
ここで種結晶としては、初回においては５ｒＴｉ０３の
［１００］単結晶を用いた。そして５ｒＬａ’Ｇａ０４
単結晶が得られた後は、当該結晶の［１００］方位の単
結晶を種結晶として用いた。Here, as a seed crystal, a [100] single crystal of 5rTi03 was used at the first time. And 5rLa'Ga04
After the single crystal was obtained, the [100] oriented single crystal of the crystal was used as a seed crystal.
結晶の引上げ条件は、引上げ速度１ｍｍ／Ｈｒ、結晶回
転速度２５ｒｐｍで、直径３０ｍｍ、長さ７０ｍｍの［
１００］軸単結晶を得ることかできた。The crystal pulling conditions were a pulling speed of 1 mm/Hr, a crystal rotation speed of 25 rpm, and a [
100] axis single crystal could be obtained.
このようにして、形成されたＳｒＬａＧａＯ４単結晶を
スライスし、超伝導体薄膜形成用基板が完成する。The SrLaGaO4 single crystal thus formed is sliced to complete a substrate for forming a superconductor thin film.
そして次に、通常のＭＢＥ法により、ＹＢａ２Ｃｕ３０
薄膜パターン２を形成する。このとき基板上にメ
タルマスクを介して選択的に薄膜を形成することにより
パターン形成を行う。Then, by normal MBE method, YBa2Cu30
A thin film pattern 2 is formed. At this time, pattern formation is performed by selectively forming a thin film on the substrate via a metal mask.
そして、第２図に示すようなＭＢＥ装置を使用し、電子
ビームをあてるかまたはにセルを用いて、Ｓｒ、Ｌａ、
Ｇａの分子線を飛ばし、酸素雰囲気中で基板上にＳ ｒ
ＬａＧａｏ４Ｎ膜からなる絶縁膜パターン３を形成する
。このＭＢＥ装置は真空容器２０内にそれぞれＳｒ、Ｌ
ａ、Ｇａの入った白金るつは２１，２２．２３を配設し
、この白金るつほに電子ビームを照射し、基板ヒータを
兼ねた載置台２４上の基板１上に５ｒＬａＧａ０４薄膜
を堆積するものである。Then, using an MBE apparatus as shown in FIG. 2, by applying an electron beam or using a cell, Sr, La,
A molecular beam of Ga is ejected, and Sr is deposited on the substrate in an oxygen atmosphere.
An insulating film pattern 3 made of a LaGao4N film is formed. This MBE apparatus has Sr and L in the vacuum container 20, respectively.
a, Ga-containing platinum melts 21, 22, and 23 are arranged, and the platinum melts are irradiated with an electron beam to deposit a 5rLaGa04 thin film on the substrate 1 on the mounting table 24, which also serves as a substrate heater. It is something to do.
そしてさらにＭＢＥ法により、メタルマスクを介してＹ
Ｂａ２ Ｃｕ３０ 薄膜パターン４を形成する。Furthermore, using the MBE method, Y
A Ba2Cu30 thin film pattern 4 is formed.
５ｒＬａＧａ０４単結晶の格子定数は３．８５人で、Ｙ
Ｂａ２ Ｃｕ３０ 薄膜に対する格子定数の差は１
，３％と極めて小さい。また、結晶構造も極めて近く、
５ｒＬａＧａＣ）＋単結晶のＹＢａ２ Ｃｕ３０
薄膜との格子整合性は極めて優７−δ
れており、前述した条件の全てを具備しており、格子歪
の小さい良質の積層構造を得ることができる。The lattice constant of 5rLaGa04 single crystal is 3.85, and Y
The difference in lattice constant for Ba2 Cu30 thin film is 1
, 3%, which is extremely small. In addition, the crystal structure is very similar,
5rLaGaC) + single crystal YBa2 Cu30
The lattice matching with the thin film is extremely excellent (7-δ), and all of the above-mentioned conditions are met, making it possible to obtain a high-quality laminated structure with small lattice strain.
このようにして極めて特性が良好で信頼性の高いジョゼ
フソントンネル素子を得ることができる。In this way, a Josephson tunnel element with extremely good characteristics and high reliability can be obtained.
なお、この例では、Ｓ／Ｉ／Ｓのトンネル接合を用いた
ジョゼフソントンネル素子について説明したが、超伝導
薄膜パターンのうち一方のみを超伝導領域温度で使用し
た、Ｓ ／ Ｉ ／ Ｎ （５ｕｐｅｒｃｏｎｄｕｃｔ
ｏｒ／Ｉｎ５ｕｌａｔｏｒ／ Ｎｏｒｍａｌ）型のトン
ネル接合素子等、他の超伝導素子にも適用可能である。In addition, in this example, a Josephson tunnel element using an S/I/S tunnel junction was explained, but an S/I/N (5upperconducting
It is also applicable to other superconducting elements, such as tunnel junction elements of the or/In5ulator/Normal) type.
実施例２ 次に本発明の第２の実施例について説明する。Example 2 Next, a second embodiment of the present invention will be described.
第３図は本発明の第２の実施例のジョゼフソントンネル
素子を示す図である。FIG. 3 is a diagram showing a Josephson tunnel element according to a second embodiment of the present invention.
この素子は、バッファ膜としてＳｒＬａＧａＯ４単結晶
薄膜を介して超伝導薄膜を形成したことを特徴とするも
のである。This device is characterized in that a superconducting thin film is formed as a buffer film via a SrLaGaO4 single crystal thin film.
すなわち、この素子はＭｇＯ単結晶基板１コ上に組成が
次式に示すようなに２ＮｉＦ４型の結晶構造を有する、
Ｓ ｒ Ｉ−Ｌ ａ ）−Ｇ ａ ＋−ｒ ０４−ｗ（
−０，０５＜ｘ ＜０．０５．−０．０５ ＜ｙ ＜０
．０５．−ｏ、。That is, this element has a 2NiF4 type crystal structure with a composition shown in the following formula on one MgO single crystal substrate, S r I-L a )-G a +-r 04-w (
−0,05<x<0.05. -0.05 <y <0
．． 05. -o,.
５ ＜、ｚ ＜０．０５ 、−０．２＜Ｗ ＜０．２
）膜厚 のストロンチウム−ランタン−ガリウム系
酸化物単結晶薄膜１２を形成し、この上に、Ｙ１３ａ２
Ｃｕ３０ 薄膜パターン２と、この基板７−δ
と同一組成の５ｒＬａＧａ０４薄膜からなる絶縁膜パタ
ーン３とを当接せしめ、さらにこの絶縁膜パターン３の
上層にＹＢａ２ Ｃｕ３０ 薄膜パフ−δ
ターン４を形成したものである。5 <, z <0.05, -0.2 <W <0.2
) A strontium-lanthanum-gallium-based oxide single crystal thin film 12 with a film thickness of
A Cu30 thin film pattern 2 is brought into contact with an insulating film pattern 3 made of a 5rLaGa04 thin film having the same composition as this substrate 7-δ, and a YBa2 Cu30 thin film puff-δ turn 4 is formed on the upper layer of this insulating film pattern 3. It is.
この場合、ＭｇＯ単結晶基板上にＳｒＬａＧａＯ４単結
晶薄膜を介して超伝導薄膜が形成されているため、格子
定数の差による結晶歪もなく良好なエピタキシャル膜が
形成されており、特性が良好でかつ製造歩留まりも良好
なものとなっている。In this case, since the superconducting thin film is formed on the MgO single crystal substrate via the SrLaGaO4 single crystal thin film, a good epitaxial film is formed without crystal distortion due to differences in lattice constants, and has good characteristics. The manufacturing yield is also good.
なお、これらの実施例に限定されることなく、他の酸化
物超伝導薄膜の形成にも適用可能である。Note that the present invention is not limited to these examples and can be applied to the formation of other oxide superconducting thin films.
また、前記実施例では絶縁膜、バッファ膜および超電導
酸化物薄膜を形成するに際し、ＭＢＥ法の他、ＲＦマグ
ネトロンスパッタ法、ＡＲＥ法、レーザアブレーション
法、多元レーザアブレーション法、多元イオンクラスタ
ービーム法、真空蒸着法、多元蒸着（ＭＳＤ）法、分子
線エピタキシー（ＭＢＥ法）、ＣＶＤ法等を用いてもよ
い。In addition to the MBE method, RF magnetron sputtering method, ARE method, laser ablation method, multidimensional laser ablation method, multidimensional ion cluster beam method, vacuum A vapor deposition method, a multi-dimensional deposition (MSD) method, a molecular beam epitaxy (MBE method), a CVD method, etc. may be used.
以上説明してきたように、本発明によれば、特性が良好
で信頼性の高い超伝導素子を得ることが可能となる。As described above, according to the present invention, it is possible to obtain a superconducting element with good characteristics and high reliability.
第１図は、本発明の第１の実施例のジョゼフソントンネ
ル接合素子を示す図、第２図は同素子の製造工程で用い
るＭＢＥ装置を示す図、第３図は本発明の第２の実施例
のジョゼフソントンネル接合素子を示す図である。
１−・−３ｒＴｉ０３基板、２．４−ＹＢａ２Ｃｕ５０
薄膜、３−５ｒＬａＧａ０４単結晶薄膜７−δ
（絶縁膜） 、１１ ・−ＭｇＯ基板、１２− Ｓ ｒ
Ｌ ａＧａｚ４ （バッファ膜）、２０・・・真空容
器、２１゜２２゜
３・・・白金るつは゛、
２４・・・載置台。
第
図
第
図FIG. 1 is a diagram showing a Josephson tunnel junction device according to a first embodiment of the present invention, FIG. 2 is a diagram showing an MBE apparatus used in the manufacturing process of the same device, and FIG. 3 is a diagram showing a second embodiment of the Josephson tunnel junction device according to the present invention. FIG. 2 is a diagram showing a Josephson tunnel junction device according to an example. 1-・-3rTi03 substrate, 2.4-YBa2Cu50
Thin film, 3-5rLaGa04 single crystal thin film 7-δ (insulating film), 11 ・-MgO substrate, 12-S r
L aGaz4 (buffer film), 20... Vacuum container, 21゜22゜3... Platinum glass, 24... Mounting table. Figure Figure
Claims (2)
伝導薄膜パターンとによって絶縁膜を挾みトンネル接合
を含む構造体を形成してなる超伝導素子において、 前記絶縁膜がＳｒＬａＧａＯ＿４薄膜で構成されている
ことを特徴とする超伝導素子。(1) A superconducting element in which a structure including a tunnel junction is formed by sandwiching an insulating film between a first superconducting thin film pattern and a second superconducting thin film pattern on a substrate, wherein the insulating film is SrLaGaO_4 A superconducting element characterized by being composed of a thin film.
備した超伝導素子において、 基板上にＳｒＬａＧａＯ＿４薄膜を介して前記構造体を
形成したことを特徴とする超伝導素子。(2) A superconducting element comprising a structure including a superconducting thin film pattern on a substrate, characterized in that the structure is formed on the substrate via a SrLaGaO_4 thin film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2180973A JPH0467692A (en) | 1990-07-09 | 1990-07-09 | Superconducting element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2180973A JPH0467692A (en) | 1990-07-09 | 1990-07-09 | Superconducting element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0467692A true JPH0467692A (en) | 1992-03-03 |
Family
ID=16092519
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2180973A Pending JPH0467692A (en) | 1990-07-09 | 1990-07-09 | Superconducting element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0467692A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0656581A (en) * | 1992-08-07 | 1994-03-01 | Nippon Telegr & Teleph Corp <Ntt> | Formation of single crystal thin film of oxide high-temperature superconductor and substrate for formation of single crystal thin film of oxide high-temperature superconductor and its formation |
-
1990
- 1990-07-09 JP JP2180973A patent/JPH0467692A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0656581A (en) * | 1992-08-07 | 1994-03-01 | Nippon Telegr & Teleph Corp <Ntt> | Formation of single crystal thin film of oxide high-temperature superconductor and substrate for formation of single crystal thin film of oxide high-temperature superconductor and its formation |
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