Atomic-Scale Scanning of Domain Network in the Ferroelectric HfO2 Thin Film,ACS Nano

当前位置： X-MOL 学术 › ACS Nano › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Atomic-Scale Scanning of Domain Network in the Ferroelectric HfO2 Thin Film
ACS Nano ( IF 15.8 ) Pub Date : 2024-09-12 , DOI: 10.1021/acsnano.4c08721
Kunwoo Park _{1,

2} , Dongmin Kim _{1,

2,

3} , Kyoungjun Lee ₄ , Hyun-Jae Lee ₅ , Jihoon Kim _{1,

2} , Sungsu Kang _{1,

2} , Alex Lin ₆ , Alexander J Pattison ₆ , Wolfgang Theis ₇ , Chang Hoon Kim ₅ , Hyesung Choi _{1,

2} , Jung Woo Cho ₄ , Peter Ercius ₆ , Jun Hee Lee ₅ , Seung Chul Chae ₄ , Jungwon Park _{1,

2,

8,

9}

Affiliation

Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea.
School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Seoul 08826, Republic of Korea.
Samsung Advanced Institute of Technology, Samsung Electronics, Suwon-si, Gyeonggi-do 16678, Republic of Korea.
Department of Physics Education, Seoul National University, Seoul 08826, Republic of Korea.
Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K.
Institute of Engineering Research, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea.
Advanced Institute of Convergence Technology, Seoul National University, Suwon-si, Gyeonggi-do 16229, Republic of Korea.

Ferroelectric HfO₂-based thin films have attracted much interest in the utilization of ferroelectricity at the nanoscale for next-generation electronic devices. However, the structural origin and stabilization mechanism of the ferroelectric phase are not understood because the film is typically nanocrystalline with active yet stochastic ferroelectric domains. Here, electron microscopy is used to map the in-plane domain network structures of epitaxially grown ferroelectric Y:HfO₂ films in atomic resolution. The ferroelectricity is confirmed in free-standing Y:HfO₂ films, allowing for investigating the structural origin for their ferroelectricity by 4D-STEM, high-resolution STEM, and iDPC-STEM. At the grain boundaries of <111>-oriented Pca2₁ orthorhombic grains, a high-symmetry mixed-(R3m, Pnm2₁) phase is induced, exhibiting enhanced polarization due to in-plane compressive strain. Nanoscale Pca2₁ orthorhombic grains and their grain boundaries with mixed-(R3m, Pnm2₁) phases of higher symmetry cooperatively determine the ferroelectricity of the Y:HfO₂ film. It is also found that such ferroelectric domain networks emerge when the film thickness is beyond a finite value. Furthermore, in-plane mapping of oxygen positions overlaid on ferroelectric domains discloses that polarization is suppressed at vertical domain walls, while it is active when domains are aligned horizontally with subangstrom domain walls. In addition, randomly distributed 180° charged domain walls are confined by spacer layers.

中文翻译：

铁电 HfO2 薄膜中域网络的原子级扫描

铁电HfO ₂基薄膜引起了人们对纳米级铁电在下一代电子器件中的利用的极大兴趣。然而，铁电相的结构起源和稳定机制尚不清楚，因为该薄膜通常是具有活性但随机铁电域的纳米晶体。在这里，电子显微镜用于以原子分辨率绘制外延生长的铁电Y:HfO ₂薄膜的面内域网络结构。独立式 Y:HfO ₂薄膜中的铁电性得到证实，从而可以通过 4D-STEM、高分辨率 STEM 和 iDPC-STEM 研究其铁电性的结构起源。在<111>取向的Pca2 ₁斜方晶粒的晶界处，诱导出高对称性混合( R 3 m ，Pnm2 ₁ )相，由于面内压缩应变而表现出增强的极化。纳米级Pca2 ₁正交晶粒及其具有较高对称性的混合( R 3 m , Pnm2 ₁ )相的晶界共同决定了Y:HfO ₂薄膜的铁电性。还发现，当薄膜厚度超过有限值时，就会出现这种铁电畴网络。此外，覆盖在铁电域上的氧位置的面内映射揭示了极化在垂直域壁处被抑制，而当域与亚埃域壁水平对准时极化是活跃的。此外，随机分布的 180° 带电畴壁受到间隔层的限制。

更新日期：2024-09-12

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南