Fabrication of HfO2-based multiferroelctric ultrathin films by controlling crystalline phase
| Project/Area Number |
16K18231
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Keywords | HfO2基材料 / 超薄膜 / 準安定相 / 強誘電性 / エピタキシャル成長 / 蛍石型酸化物 / 斜方晶相 / ドーパント添加 / ドメイン構造 / 相転移温度 / フェロイック特性 |
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| Outline of Final Research Achievements |
The purpose of this research is the fabrication of multiferroic HfO2-based ultrathin films. By adding the magnetic elements to HfO2 ultrathin films, its ucceeded in forming a metastable orthorhombic phase, and ferroelectricty arising from that phase was elarly observed. In additon, the films had a high Curie temperature above 400 ℃.In the case of Ce which is a non-magnetic element, it has been found that the formation of an orthorhombic phase is dramatically promoted, and the multidomain structures composed of orthorhombic phase was observed. Therefore, it was demonstrated that Ce doped HfO2 ultrathin films are a strong candidate for fluorite-type ferroelectrics.
From the detailed investigation of the relationship between the dopant and the crystalline phase, we obtained an one of the material design guidelines for the fabrication of ferroelectric HfO2-based ultrathin films.
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| Academic Significance and Societal Importance of the Research Achievements |
IoT社会の実現において不可欠となる、高性能な省エネルギー小型デバイスの開発に向けて、機能性材料のナノスケール化が盛んに行われている。強誘電体材料もその一つであり、種々の元素を添加したHfO2基超薄膜は、ナノスケールで実用可能な強誘電体として注目されている。しかし、材料設計指針は確立されておらず、強誘電性の制御には至っていない。本研究は、構造解析により、添加元素と結晶相の関係を解明することで、結晶相の制御だけでなく、ドメインといった組織制御の必要性を提案した。また、有力な添加元素を見出したことで、強誘電性の向上が期待される。
得られた知見は、次世代の強誘電体デバイス開発の一助になると考えている。
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Report
(4 results)
Research Products
(11 results)
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[Journal Article] Effect of the film thickness on the crystal structure and ferroelectric properties of (Hf0.5Zr0.5)O2 thin films deposited on various substrates2017
Author(s)
T. Shiraishi, K. Katayama, T. Yokouchi, T. Shimizu, T. Oikawa, O. Sakata, H. Uchida, Y. Imai, T. Kiguchi, T. J. Konno, and H. Funakubo
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Journal Title
Mater. Sci. Semicond. Process
Volume: 印刷中
Related Report
Peer Reviewed / Acknowledgement Compliant
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