Intrinsic ferroelectricity in Y-doped HfO2 thin films
Intrinsic ferroelectricity in Y-doped HfO2 thin films
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DOI：
10.1038/s41563-022-01282-6
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发表时间：
2021-09
期刊：
影响因子：
41.2
通讯作者：
Yu Yun;P. Buragohain;Ming Li;Z. Ahmadi;Yizhi Zhang;Xin Li;Haohan Wang;Jing Li;P. Lu;L. Tao;Haiyan Wang;J. Shield;E. Tsymbal;A. Gruverman;Xiaoshan Xu
中科院分区：
文献类型：
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作者：
Yu Yun;P. Buragohain;Ming Li;Z. Ahmadi;Yizhi Zhang;Xin Li;Haohan Wang;Jing Li;P. Lu;L. Tao;Haiyan Wang;J. Shield;E. Tsymbal;A. Gruverman;Xiaoshan Xu
由于铁电 HfO2 基材料与现有硅技术的兼容性，因此在将铁电广泛集成到现代电子产品中具有巨大潜力。早期的工作表明，纳米晶粒尺寸对于铁电相的稳定至关重要。这种限制与高密度的结构缺陷相关，模糊了对 HfO2 基材料的固有铁电性的深入了解。在这里，我们证明了具有高度结构有序性（结晶度）的外延 HfO2 薄膜可以实现稳定且增强的偏振。在室温下，Y 掺杂 HfO2(111) 外延薄膜中观察到面外极化值为 50μCcm–2，估计本征极化全值为 64μCcm–2，这与密度泛函理论计算非常一致。薄膜的晶体结构揭示了具有小菱面体畸变的Pca21正交相，强调了结构约束在稳定铁电相中的作用。我们的结果表明，可以利用 HfO2 基材料的固有铁电性，优化其在设备应用中的性能。
Ferroelectric HfO2-based materials hold great potential for the widespread integration of ferroelectricity into modern electronics due to their compatibility with existing Si technology. Earlier work indicated that a nanometre grain size was crucial for the stabilization of the ferroelectric phase. This constraint, associated with a high density of structural defects, obscures an insight into the intrinsic ferroelectricity of HfO2-based materials. Here we demonstrate that stable and enhanced polarization can be achieved in epitaxial HfO2films with a high degree of structural order (crystallinity). An out-of-plane polarization value of 50 μC cm–2has been observed at room temperature in Y-doped HfO2(111) epitaxial thin films, with an estimated full value of intrinsic polarization of 64 μC cm–2, which is in close agreement with density functional theory calculations. The crystal structure of films reveals thePca21orthorhombic phase with small rhombohedral distortion, underlining the role of the structural constraint in stabilizing the ferroelectric phase. Our results suggest that it could be possible to exploit the intrinsic ferroelectricity of HfO2-based materials, optimizing their performance in device applications.