Solid state epitaxy of (Hf,Zr)O2 thin films with orthorhombic phase

• KIGUCHI Takanori

  Institute for Materials Research, Tohoku University

• NAKAMURA Shogo

  Department of Materials Science, Tohoku University

• AKAMA Akihiro

  Institute for Materials Research, Tohoku University

• SHIRAISHI Takahisa

  Institute for Materials Research, Tohoku University

• KONNO Toyohiko J.

  Institute for Materials Research, Tohoku University

書誌事項

タイトル別名

• Solid state epitaxy of (Hf,Zr)O₂ thin films with orthorhombic phase

抄録

Hf_0.5Zr_0.5O₂ (HZO) thin films with orthorhombic phase Pca2₁ are novel ferroelectric materials. We have attempted the epitaxial growth of HZO thin films using solid-state epitaxy with ion-beam sputtering followed by rapid thermal annealing. X-ray diffraction (XRD) profiles of HZO thin films on SiO₂ glass substrates showed {111}-oriented monoclinic and orthorhombic phases. On the other hand, XRD profiles of HZO on yttria stabilized zirconia (YSZ) (100) substrates indicated the shoulder peak on the strong tail of 200 peak of YSZ substrates in the lower 2θ side. Structural analyses of the HZO thin films have conducted to identify constituent phases, the local orientation, and the nanostructure of HZO thin films using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and the related STEM-EDS analysis. In this paper, we have described the orthorhombic (Pca2₁) and monoclinic (P2₁/c) phases coexisted based on multislice image simulation and diffractogram analysis of the local regions in HZO thin films. The principal phase in the HZO/YSZ epitaxial thin films is the orthorhombic phase. Each phase was epitaxially grown on the YSZ substrate with a domain structure of the order of 10 nm in size. The orthorhombic phase has formed in the HZO/SiO₂ glass thin films, which indicates that the stability of the orthorhombic phase is ascribed to not only pseudomorphic or lattice mismatch effects of the substrate but also doping effects and thermal mismatch between the film and the substrate. The mosaicity of thin film is high because of lattice deformation with coexisting monoclinic phase and a damaged region between thin film and substrate caused by sputtered particles with high energy. Orthorhombic single-phase thin films with higher quality can be obtained by preparing ultrathin HZO epitaxial thin films under lower Ar-ion beam energy in the sputtering process and the higher crystallization temperature in the post-annealing process.

収録刊行物

• Journal of the Ceramic Society of Japan

  Journal of the Ceramic Society of Japan 124 (6), 689-693, 2016

  公益社団法人 日本セラミックス協会

キーワード

• HfO₂
• ZrO₂
• Thin film
• Solid-state epitaxy
• Orthorhombic phase
• Monoclinic phase
• Mosaic structure
• HAADF-STEM

詳細情報

• CRID: 1390001205285314304
• NII論文ID: 130005155642
• DOI: 10.2109/jcersj2.16073
• ISSN: 13486535
• ISSN: 18820743
• Web Site: https://www.jstage.jst.go.jp/article/jcersj2/124/6/124_16073/_pdf
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可