JP2855164B2 - Method for producing alkali metal substituted oxide thin film - Google Patents
Method for producing alkali metal substituted oxide thin filmInfo
- Publication number
- JP2855164B2 JP2855164B2 JP1135367A JP13536789A JP2855164B2 JP 2855164 B2 JP2855164 B2 JP 2855164B2 JP 1135367 A JP1135367 A JP 1135367A JP 13536789 A JP13536789 A JP 13536789A JP 2855164 B2 JP2855164 B2 JP 2855164B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- alkali metal
- oxide thin
- oxide
- oxygen
- 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 - Lifetime
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
Description
【発明の詳細な説明】 （発明の産業上の利用分野） 本発明はアルカリ金属置換酸化物薄膜の製造方法、さ
らに詳細にはアルカリ金属が多量に置換された酸化物薄
膜の製造方法に関するものである。Description: TECHNICAL FIELD The present invention relates to a method for producing an alkali metal-substituted oxide thin film, and more particularly to a method for producing an oxide thin film in which a large amount of alkali metal is substituted. is there.
（従来技術および問題点） アルカリ金属のイオン半径はいずれも大きい。このた
め、格子を組む金属をアルカリ金属イオンで置換した材
料を作製しようとする場合、特別の工夫が必要で、しか
も置換量にも上限があった。特に、酸化物を作製しよう
とする場合、アルカリ金属の酸化物は析出され易く、逆
にこの特性から酸化物単結晶育成の溶媒としてアルカリ
金属化合物が用いられていたほどである。このため、ア
ルカリ金属を含有する酸化物を得るには、還元雰囲気下
でアルカリ金属の置換を行ない、その後、低温で、酸素
中熱処理を行なう方法が用いられている。しかし、この
方法ではアルカリ金属の分布が不均一で、酸素欠陥も残
り易く、また、置換量も熱的な固溶限界で制限され、不
充分な特性しか得られていなかった。その他、アルカリ
金属の酸化物は化学的に不安定で取り扱い上も問題が多
いことが制約となっていた。(Prior Art and Problems) The ionic radius of each alkali metal is large. For this reason, when trying to produce a material in which the metal forming the lattice is replaced with alkali metal ions, a special device is required, and the replacement amount has an upper limit. In particular, when an oxide is to be produced, an oxide of an alkali metal is easily precipitated. On the contrary, an alkali metal compound has been used as a solvent for growing an oxide single crystal because of this characteristic. For this reason, in order to obtain an oxide containing an alkali metal, a method of performing substitution of the alkali metal in a reducing atmosphere and then performing a heat treatment in oxygen at a low temperature is used. However, in this method, the distribution of the alkali metal is uneven, oxygen vacancies are likely to remain, and the amount of substitution is limited by the thermal solid solution limit, resulting in insufficient characteristics. In addition, the alkali metal oxide is chemically unstable and has many problems in handling.
ところで、酸化物超伝導材料を作製する上でキャリア
の導入が重要となっている。その場合、価数の小さいア
ルカリ金属の置換は有効であり、実際BaBiO3のBaをＫに
置換することで、超伝導転移温度Tcが30Kを越えるセラ
ミックス材料も実現している。ただし、従来のセラミッ
クス作製技術では、複雑な工程を厳密に制御しないとセ
ラミックスは得にくく、しかも良質の超伝導特性を得る
には至っていない。また、Ｋの置換量も40％以下に制限
されていた。By the way, introduction of a carrier is important in manufacturing an oxide superconducting material. In this case, the substitution of an alkali metal having a small valence is effective. In fact, by substituting Ba of BaBiO 3 with K, a ceramic material having a superconducting transition temperature Tc of more than 30 K has been realized. However, in the conventional ceramic manufacturing technique, it is difficult to obtain ceramics unless a complicated process is strictly controlled, and furthermore, high quality superconductivity has not been obtained. Further, the substitution amount of K was limited to 40% or less.
本発明は、上述の問題点に鑑みなされたものであり、
その目的はアルカリ金属を含む酸化物材料の薄膜を容易
に作製することにある。The present invention has been made in view of the above problems,
The purpose is to easily produce a thin film of an oxide material containing an alkali metal.
（問題点を解決するための手段） 上記問題点を解決するため、本発明によるアルカリ金
属置換酸化物薄膜の製造方法は、BaBiO3を母結晶とし、
主要構成元素をアルカリ金属で置換したアルカリ金属置
換酸化物薄膜の製造方法において、前記酸化物の構成材
料から真空蒸着によって酸化物薄膜を形成する際、同時
に酸素イオンを40〜60eVのエネルギで照射することを特
徴とするものである。(Means for Solving the Problems) In order to solve the above problems, the method for producing an alkali metal substituted oxide thin film according to the present invention uses BaBiO 3 as a mother crystal,
In the method for manufacturing an alkali metal-substituted oxide thin film in which main constituent elements are replaced with an alkali metal, when forming an oxide thin film by vacuum deposition from the constituent material of the oxide, simultaneously irradiate oxygen ions with an energy of 40 to 60 eV. It is characterized by the following.
本発明をさらに詳しく説明する。 The present invention will be described in more detail.
真空蒸着法は、構成元素を原子単位まで分解し、その
後混合させるため、混合相が作りにくい材料系あるいは
非平衡相を合成する手段として有効である。ただし、酸
化物のように構成元素に酸素を含む材料系では真空中で
合成すると酸素欠陥ができ易く、それを補償するための
熱処理工程が必要となり、平衡相に戻ってしまうことに
なる。そこで真空中蒸着にもかかわらず、充分な酸化が
行なえる酸素イオンを同時に照射することにより非平衡
状態の酸化膜を作ることができる。The vacuum deposition method is effective as a means for synthesizing a material system or a non-equilibrium phase in which a mixed phase is difficult to be formed because constituent elements are decomposed into atomic units and then mixed. However, in a material system containing oxygen as a constituent element, such as an oxide, when it is synthesized in a vacuum, oxygen vacancies are easily generated, and a heat treatment step for compensating the oxygen vacancies is required, and the phase returns to an equilibrium phase. Therefore, a non-equilibrium oxide film can be formed by simultaneously irradiating oxygen ions capable of performing sufficient oxidation despite the vacuum deposition.
前述のように真空蒸着中に酸素イオンを同時に照射す
るものであるが、この酸素イオンは40〜60eVのエネルギ
で照射する。40eV未満であると酸素イオン量が少なく、
良好な酸化物膜ができない恐れがあり、一方60eVを越え
ると、運動エネルギが大きすぎてスパッタ効果による膜
圧減少が著しくなるという欠点を生じるからである。As described above, oxygen ions are simultaneously irradiated during vacuum deposition, and the oxygen ions are irradiated at an energy of 40 to 60 eV. If it is less than 40 eV, the amount of oxygen ions is small,
This is because there is a possibility that a good oxide film cannot be formed. On the other hand, if it exceeds 60 eV, the kinetic energy is too large, and a disadvantage that the film pressure is significantly reduced due to the sputtering effect occurs.
この酸素ガスの流量は、3SCCM以上であるのが好まし
い。3SCCM未満であると、酸素量が少なすぎて良好な酸
化物膜賀できない恐れがあるからである。一方、前記酸
素の流量の上限は、成膜系の真空度によって左右され
る。この成膜系の真空度は、10-5Torr以上の高真空であ
ることが好ましい。真空度が10-5Torrに満たない低真空
であると真空蒸着における成膜が良好に行かない恐れを
生じるからである。The flow rate of the oxygen gas is preferably 3 SCCM or more. If it is less than 3 SCCM, the amount of oxygen may be too small and a good oxide film may not be formed. On the other hand, the upper limit of the flow rate of oxygen depends on the degree of vacuum of the film forming system. The degree of vacuum of this film forming system is preferably a high vacuum of 10 -5 Torr or more. This is because if the degree of vacuum is lower than 10 −5 Torr, there is a risk that film formation by vacuum deposition may not be performed well.
なお、本発明に用いる母結晶は、BaBiO3である。The mother crystal used in the present invention is BaBiO 3 .
以下実施例をもとに詳しく説明を行なう。 Hereinafter, a detailed description will be given based on embodiments.
（実施例１） SrTiO3基板あるいはMgOの基板１面上に、第１図の装
置を用いてBa1-xKxBiO3の薄膜を形成させるものであ
る。(Example 1) SrTiO 3 substrate or MgO substrate 1 side on, but to form a thin film of Ba 1-x KxBiO 3 using the apparatus of Figure 1.
第１図より明らかなように、本発明による酸化物薄膜
製造装置は、基板１とこの基板を支持する基板ホルダ２
をエピ成長室３内に有しており、このエピ成長室３に
は、中和機構９、減速機構10、質量分離器11およびイオ
ンソース12よりなる酸素イオン源４が設けられており、
前記基板ホルダ２に支持された基板１に酸素ビーム７を
照射可能になっている。As is apparent from FIG. 1, the apparatus for manufacturing an oxide thin film according to the present invention comprises a substrate 1 and a substrate holder 2 for supporting the substrate.
In the epi-growth chamber 3, and the epi-growth chamber 3 is provided with a neutralization mechanism 9, a reduction mechanism 10, a mass separator 11, and an oxygen ion source 4 including an ion source 12.
The substrate 1 supported by the substrate holder 2 can be irradiated with an oxygen beam 7.
前記エピ成長室３内の下部にはＫセル５が備えられて
おり、金属元素ビーム７を発し、前記金属元素による蒸
着膜が基板１に形成されるようになっている。なお、８
は予備排気室である。A K cell 5 is provided at a lower portion in the epi-growth chamber 3, emits a metal element beam 7, and a deposition film of the metal element is formed on the substrate 1. In addition, 8
Is a preliminary exhaust chamber.
まず、第１図の装置中の基板ホルダー２に基板１を取
付ける。First, the substrate 1 is mounted on the substrate holder 2 in the apparatus shown in FIG.
エピ成長室３内の真空度を10-5Torr以下とし、基板温
度を500℃として、Ｋセル５から、Ｋ、Ba、Biの金属を
蒸着させ基板１に堆積膜を形成させる。With the degree of vacuum in the epi growth chamber 3 set to 10 −5 Torr or less and the substrate temperature set to 500 ° C., K, Ba, and Bi metals are deposited from the K cell 5 to form a deposited film on the substrate 1.
この堆積膜を形成するに際し、イオンソース12で高エ
ネルギで発生させた酸素イオンを質量分離器11によって
純粋化したのち、前記酸素ビーム７を減速機構10によっ
て減速させ、堆積膜に酸素ビーム７を50eVで打ち込ん
だ。このようにしてペロブスカイト構造を持つBa1-xKxB
iO3薄膜をエピタキシャル成長させた。In forming this deposited film, oxygen ions generated at high energy in the ion source 12 are purified by a mass separator 11, and then the oxygen beam 7 is decelerated by a reduction mechanism 10, and the oxygen beam 7 is applied to the deposited film. Driven at 50 eV. Ba 1-x KxB with perovskite structure in this way
An iO 3 thin film was grown epitaxially.
BaとＫの組成比は、各Ｋセルの温度を変えることによ
り蒸発速度を制御することにより、ｘ＝０からｘ＝0.8
まで得た。The composition ratio of Ba and K can be adjusted from x = 0 to x = 0.8 by controlling the evaporation rate by changing the temperature of each K cell.
I got it.
なお酸素イオン源４の中和装置９は前記基板に形成さ
れた堆積膜の帯電を防止するためのものである。The neutralizing device 9 of the oxygen ion source 4 is for preventing the deposited film formed on the substrate from being charged.
第２図に得られた薄膜のＸ線回折パターンを示す。回
折ピークより、SrTiO3およびMgO基板上にBa1-xKxBiO3薄
膜がエピタキシャル成長していることがわかる。FIG. 2 shows an X-ray diffraction pattern of the obtained thin film. The diffraction peak shows that the Ba 1-x KxBiO 3 thin film is epitaxially grown on the SrTiO 3 and MgO substrates.
第３図にＸ線回折パターンから得られた格子定数とEP
MAより求めたK/Bi比の関係を示す。従来ｘが0.4以下で
の領域しか明らかにされていなかったが、本発明の酸化
物薄膜によりほぼ全領域にわたって格子定数とＫ置換量
の関係がわかる。Figure 3 shows the lattice constant and EP obtained from the X-ray diffraction pattern.
The K / Bi ratio obtained from MA is shown. Conventionally, only the region where x is 0.4 or less has been clarified, but the relationship between the lattice constant and the K substitution amount can be understood over almost the entire region by the oxide thin film of the present invention.
このように、本発明で述べた蒸着法によりｘ＜0.8の
領域で薄膜作製が可能である。As described above, a thin film can be formed in the region of x <0.8 by the vapor deposition method described in the present invention.
第４図に作製したアルカリ金属置換酸化物薄膜（Ba
0.7K0.3BiO3）の磁化率の温度依存性を示す。アズデボ
の非平衡状態においても（○で示す）、20K以下の温度
で反磁性が観測され超伝導体となっていることがわか
る。なお、熱処理を行ない平衡状態にすると（●で示
す）、セラミックス材料と同様にマイスナー効果は観測
されるが、第４図に示すように、非平衡状態に比べ、減
少しており、超伝導性が弱くなっている。このように本
発明により高温の置換反応過程を経ることなく超伝導特
性に優れる薄膜材料を実現することができる。The alkali metal-substituted oxide thin film (Ba
The temperature dependence of the magnetic susceptibility of 0.7 K 0.3 BiO 3 ) is shown. Even in the non-equilibrium state of as-devo (shown by ○), diamagnetism is observed at a temperature of 20 K or less, indicating that the material is a superconductor. When the heat treatment is carried out to make an equilibrium state (indicated by ●), the Meissner effect is observed similarly to the ceramic material, but as shown in FIG. Is getting weaker. As described above, according to the present invention, a thin film material having excellent superconductivity can be realized without undergoing a high-temperature substitution reaction process.
（実施例２） 実施例１と同じく、第１図に示した装置を使用しSrTi
O3またはMgO基板上にRb、Ba、Biの金属をＫセルより蒸
発させながら酸素ビームを照射し、(Ba0.7Rb0.3)BiO3を
膜厚6000Å90堆積し、第５図の特性の超伝導性薄膜を得
た。(Example 2) As in Example 1, the apparatus shown in FIG.
Rb, Ba, and Bi metals are evaporated from the K cell on an O 3 or MgO substrate and irradiated with an oxygen beam, and (Ba 0.7 Rb 0.3 ) BiO 3 is deposited to a thickness of 6000Å90, and the superconductivity shown in FIG. 5 is obtained. A functional thin film was obtained.
（発明の効果） 以上説明したように、アルカリ金属を置換した酸化物
薄膜が低温で作製できるため、酸化物超伝導体にキャリ
アを注入することおよび結晶構造を歪ませることが容易
にできる。(Effects of the Invention) As described above, since an oxide thin film in which an alkali metal is substituted can be formed at a low temperature, carriers can be easily injected into the oxide superconductor and the crystal structure can be easily distorted.
このため、非平衡組成領域の新規なアルカリ金属置換
酸化物薄膜材料が得られる。したがって、高Tc材料およ
び超伝導デバイス実現ばかりでなく、酸化物薄膜材料の
開発上の利点が大きい。Thus, a novel alkali metal-substituted oxide thin film material in the non-equilibrium composition region can be obtained. Therefore, not only the realization of a high Tc material and a superconducting device, but also a great advantage in the development of an oxide thin film material.
第１図は本発明の酸化物薄膜を作製した装置の概観図、
第２図は得られた薄膜のＸ線回折パターンで（ａ）はMg
O基板上の、（ｂ）はSrTiO3基板上の(Ba0.7K0.3)BiO3薄
膜の特性、第３図は格子定数とＫ置換量の関係、第４図
は(Ba0.7K0.3)BiO3薄膜のアズデボおよび熱処理後の磁
化率の温度変化、第５図は(Ba0.7Rb0.3)BiO3薄膜の磁化
率の温度変化である。 １……基板、２……基板ホルダー、３……エピ成長室、
４……酸素イオン源、５……Ｋセル、６……金属元素ビ
ーム、７……酸素ビーム、８……予備排気室、９……中
和機構、10……減速機構、11……質量分離器、12……イ
オンソース。FIG. 1 is a schematic view of an apparatus for producing an oxide thin film of the present invention,
FIG. 2 shows the X-ray diffraction pattern of the obtained thin film.
On the O substrate, (b) shows the characteristics of the (Ba 0.7 K 0.3 ) BiO 3 thin film on the SrTiO 3 substrate, FIG. 3 shows the relationship between the lattice constant and the K substitution amount, and FIG. 4 shows (Ba 0.7 K 0.3 ) BiO Temperature change of the magnetic susceptibility of the three thin films after as-devotion and heat treatment, and FIG. 5 shows the temperature change of the magnetic susceptibility of the (Ba 0.7 Rb 0.3 ) BiO 3 thin film. 1 ... substrate, 2 ... substrate holder, 3 ... epitaxial growth chamber,
4 ... oxygen ion source, 5 ... K cell, 6 ... metal element beam, 7 ... oxygen beam, 8 ... preliminary exhaust chamber, 9 ... neutralization mechanism, 10 ... reduction mechanism, 11 ... mass Separator, 12 ... Ion source.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平１−102975（ＪＰ，Ａ) Ｐｈｙｓ．Ｒｅｖ．Ｂ，37，Ｎｏ．７ （1988）ｐｐ．3745−3746 (58)調査した分野(Int.Cl.6，ＤＢ名) C01G 1/00 - 57/00 H01L 39/00 - 39/24 H01B 12/00──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-102975 (JP, A) Phys. Rev .. B, 37, No. 7 (1988) pp. 3745-3746 (58) Fields investigated (Int.Cl. 6 , DB name) C01G 1/00-57/00 H01L 39/00-39/24 H01B 12/00
Claims (3)
カリ金属で置換したアルカリ金属置換酸化物薄膜の製造
方法において、前記酸化物の構成材料から真空蒸着によ
って酸化物薄膜を形成する際、同時に酸素イオンを40〜
60eVのエネルギで照射することを特徴とする照射するこ
とを特徴とするアルカリ金属置換酸化物薄膜の製造方
法。1. A method for producing an alkali metal-substituted oxide thin film in which BaBiO 3 is used as a base crystal and a main constituent element is substituted by an alkali metal, wherein an oxide thin film is formed from the constituent material of the oxide by vacuum deposition. At the same time oxygen ions 40 ~
A method for producing an alkali metal substituted oxide thin film, comprising irradiating with an energy of 60 eV.
であり、その真空度は10-5Torr以上であることを特徴と
する特許請求の範囲第１項記載のアルカリ金属置換酸化
物薄膜の製造方法。2. The alkali metal-substituted oxide thin film according to claim 1, wherein the flow rate of oxygen gas in said vacuum deposition system is 3 SCC or more, and the degree of vacuum is 10 -5 Torr or more. Manufacturing method.
を特徴とする特許請求の範囲第１項または第２項記載の
いずれかのアルカリ金属置換酸化物薄膜の製造方法。3. The method according to claim 1, wherein the alkali metal is K or Rb.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1135367A JP2855164B2 (en) | 1989-05-29 | 1989-05-29 | Method for producing alkali metal substituted oxide thin film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1135367A JP2855164B2 (en) | 1989-05-29 | 1989-05-29 | Method for producing alkali metal substituted oxide thin film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03122003A JPH03122003A (en) | 1991-05-24 |
| JP2855164B2 true JP2855164B2 (en) | 1999-02-10 |
Family
ID=15150072
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1135367A Expired - Lifetime JP2855164B2 (en) | 1989-05-29 | 1989-05-29 | Method for producing alkali metal substituted oxide thin film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2855164B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2541037B2 (en) * | 1991-06-28 | 1996-10-09 | 日本電気株式会社 | Oxide superconducting thin film synthesis method |
-
1989
- 1989-05-29 JP JP1135367A patent/JP2855164B2/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| Ｐｈｙｓ．Ｒｅｖ．Ｂ，３７，Ｎｏ．７（１９８８）ｐｐ．３７４５−３７４６ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03122003A (en) | 1991-05-24 |
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