JPS6262077B2 - - Google Patents
Info
- Publication number
- JPS6262077B2 JPS6262077B2 JP58198984A JP19898483A JPS6262077B2 JP S6262077 B2 JPS6262077 B2 JP S6262077B2 JP 58198984 A JP58198984 A JP 58198984A JP 19898483 A JP19898483 A JP 19898483A JP S6262077 B2 JPS6262077 B2 JP S6262077B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- junction
- josephson
- barrier layer
- oxide
- 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.)
- Expired
Links
- 230000004888 barrier function Effects 0.000 claims description 10
- 238000005304 joining Methods 0.000 claims description 2
- 238000000151 deposition Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 230000005668 Josephson effect Effects 0.000 description 1
- 229910000978 Pb alloy Inorganic materials 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
- 230000000694 effects Effects 0.000 description 1
- 238000005566 electron beam evaporation Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000005382 thermal cycling Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Description
【発明の詳細な説明】
〔発明の利用分野〕
本発明はジヨゼフソン接合装置、特に下部電極
にNbを用いたジヨゼフソン接合装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a Jozefson bonding device, and particularly to a Jozefson bonding device using Nb for the lower electrode.
ジヨゼフソン効果を有する超電導トンネル接合
は、磁界制御によつて零電圧と有限電圧間の遷移
を起こさせることができる。このスイツチング時
間は10〜100psの範囲にあるので、ジヨゼフソン
接合はスイツチング素子としてきわめて優れてい
る。論理回路に用いるジヨゼフソン接合の形状と
してはサンドイツチ型が適している。サンドイツ
チ型接合の下部電極膜としてNbを用いた接合は
室温と液体ヘリウム温度間の熱サイクルによる劣
化がなく、特性の経時変化が少ない。しかしなが
らNb酸化膜を障壁層とするジヨゼフソン接合は
Nb酸化膜の誘電率が大きいため容量が大きくな
り、スイツチング速度が遅くなる欠点をもつてい
る。
A superconducting tunnel junction with the Josephson effect can cause a transition between zero voltage and a finite voltage by controlling the magnetic field. Since this switching time is in the range of 10 to 100 ps, the Josefson junction is extremely excellent as a switching element. The Sandermanch type is suitable as the shape of Josephson junction used in logic circuits. A sandwich-type junction using Nb as the lower electrode film does not deteriorate due to thermal cycles between room temperature and liquid helium temperature, and its characteristics change little over time. However, the Josephson junction with Nb oxide film as a barrier layer is
Since the dielectric constant of the Nb oxide film is high, the capacitance is large and the switching speed is slow.
本発明はNbを下部電極としてジヨゼフソン接
合のこのような問題点を解決し、容量によるスイ
ツチング時間遅れの少ないジヨゼフソン接合の構
造を与えることにある。
The object of the present invention is to solve these problems of the Josephson junction by using Nb as the lower electrode, and to provide a composition of the Josephson junction with less switching time delay due to capacitance.
本発明では第１図のようなサンドイツチ型ジヨ
ゼフソン接合において、障壁層３をSiの酸化物と
する。下部電極膜２はNb、上部電極膜４はPb、
Pb合金あるいはNbなど臨界温度が液体ヘリウム
温度以上の超電導材料である。
In the present invention, the barrier layer 3 is made of Si oxide in the Sand-Deutsch-type Josefson junction as shown in FIG. The lower electrode film 2 is made of Nb, the upper electrode film 4 is made of Pb,
A superconducting material such as Pb alloy or Nb whose critical temperature is higher than the liquid helium temperature.
障壁層となる上記Siの酸化物は、厚さ１〜
10nmのSi膜層の一部あるいは全部を酸化せしめ
てなるものである。Si膜層の厚さが1nm未満では
ピンポールが多くなりSi酸化物の障壁層としての
特性が認められず、10nmを越えると電極間のカ
ツプリングが低下するためリークが多くなりジヨ
ゼフソン電流が期待される値より低くなり、いず
れも好ましくない。 The above-mentioned Si oxide serving as the barrier layer has a thickness of 1~
It is made by partially or completely oxidizing a 10 nm Si film layer. If the thickness of the Si film layer is less than 1 nm, there will be many pin-poles, and the properties of Si oxide as a barrier layer will not be recognized. If it exceeds 10 nm, the coupling between the electrodes will decrease, leading to increased leakage and a Josephson current is expected. Both values are unfavorable.
このようなジヨゼフソン接合の製造は例えば次
のような手順で行なつた。10-5Paの真空装置中
で、あらかじめ表面を清浄化したガラス、Si、
O2、あるいはAl2O3基板１上に３nm/sの堆積速
度でNb膜を蒸着した。Nbの蒸着は電子ビーム銃
による蒸発源の加熱法によつた。Nb膜蒸着後、
真空を破ることなく別の電子ビーム蒸発源よりSi
膜を3nmのの厚さに蒸着した。しかる後に真空を
破り、大気中に１〜24時間曝すことにより、表面
のSi膜を酸化させ障壁層を形成した。この上に上
部電極膜としてPbを蒸着することによりジヨゼ
フソン接合の製作を完了した。
The manufacture of such a Josephson junction was carried out, for example, by the following procedure. In a vacuum apparatus at 10 -5 Pa, glass, Si, and
A Nb film was deposited on an O 2 or Al 2 O 3 substrate 1 at a deposition rate of 3 nm/s. Nb was deposited by heating the evaporation source using an electron beam gun. After Nb film deposition,
Si from another electron beam evaporation source without breaking the vacuum
The film was deposited to a thickness of 3 nm. Thereafter, the vacuum was broken and the film was exposed to the atmosphere for 1 to 24 hours to oxidize the Si film on the surface and form a barrier layer. The fabrication of the Josephson junction was completed by depositing Pb on top of this as the upper electrode film.
このようにして製造したNb／Si酸化物／Pbジ
ヨゼフソン接合はマイクロシヨートがなく、スイ
ツチング素子に適した直流電圧一電流特性を示
し、熱サイクルによる特性劣化はなかつた。さら
に直流ジヨゼフソン電流の印加磁界依存性および
磁場中における直流電圧一電流特性の測定から得
られた障壁層厚みと比誘電率の比は0.5〜0.7nm
であり、Nb酸化物を障壁とした接合の約５倍と
なつた。これは障壁層の厚みはほとんど変わらな
いが、Si酸化膜を障壁層とすることにより比誘電
率が1/5になつたことによるものである。したが
つて本発明によるジヨゼフソン接合は等しい面積
の接合で比較して、従来のNb接合よりスイツチ
ング速度が５倍向上する。本発明によるジヨゼフ
ソン接合は論理回路用スイツチング素子としてき
わめて有効である。 The Nb/Si oxide/Pb Josephson junction produced in this way had no microshoots, exhibited DC voltage-current characteristics suitable for switching devices, and did not deteriorate in characteristics due to thermal cycling. Furthermore, the ratio between the barrier layer thickness and relative permittivity obtained from measurements of the dependence of the DC Josefson current on the applied magnetic field and the DC voltage-current characteristics in the magnetic field is 0.5 to 0.7 nm.
This is about five times as large as the junction using Nb oxide as a barrier. This is because, although the thickness of the barrier layer remains almost the same, by using the Si oxide film as the barrier layer, the dielectric constant is reduced to 1/5. Therefore, the Josephson junction according to the invention has a switching speed five times faster than the conventional Nb junction when compared with equal area junctions. The Josefson junction according to the present invention is extremely effective as a switching element for logic circuits.
上述のように、本発明のジヨゼフソン接合装置
は下部電極をNbとしているにもかかわらず容量
が小さく、スイツチング速度が著るしく上昇し
た。
As described above, the Josephson junction device of the present invention had a small capacitance and a significantly increased switching speed despite using Nb as the lower electrode.
第１図は本発明の実施例によるジヨゼフソン接
合装置の断面図を示す。
１…ガラス基板、２…Nb膜、３…Si酸化膜、
４…Pb膜。
FIG. 1 shows a cross-sectional view of a Josephson joining device according to an embodiment of the invention. 1...Glass substrate, 2...Nb film, 3...Si oxide film,
4...Pb film.
Claims (1)
くともそなえ、上記上部電極と上記下部電極の間
には一部又は全部が酸化されたSi膜からなる障壁
層が介在していることを特徴とするジヨゼフソン
接合装置。 ２ 前記Si膜の厚さは、１〜10nmであることを
特徴とする特許請求の範囲第１項記載のジヨゼフ
ソン接合装置。[Claims] 1. At least a lower electrode made of Nb and an upper electrode are provided, and a barrier layer made of a partially or completely oxidized Si film is interposed between the upper electrode and the lower electrode. A Josephson joining device characterized by: 2. The Josephson junction device according to claim 1, wherein the thickness of the Si film is 1 to 10 nm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58198984A JPS5994481A (en) | 1983-10-26 | 1983-10-26 | Josephson junction device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58198984A JPS5994481A (en) | 1983-10-26 | 1983-10-26 | Josephson junction device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5994481A JPS5994481A (en) | 1984-05-31 |
| JPS6262077B2 true JPS6262077B2 (en) | 1987-12-24 |
Family
ID=16400175
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58198984A Granted JPS5994481A (en) | 1983-10-26 | 1983-10-26 | Josephson junction device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5994481A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01164880A (en) * | 1987-12-18 | 1989-06-28 | Maezawa Ind Inc | Valve |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110649152A (en) * | 2019-09-27 | 2020-01-03 | 江苏鲁汶仪器有限公司 | Etching method of niobium-based superconducting device |
-
1983
- 1983-10-26 JP JP58198984A patent/JPS5994481A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01164880A (en) * | 1987-12-18 | 1989-06-28 | Maezawa Ind Inc | Valve |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5994481A (en) | 1984-05-31 |
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