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近日,西安电子科技大学先进材料与纳米科技学院周益春教授团队在HfO2铁电薄膜辐照效应领域取得突破。该研究采用深度学习与排斥表相结合的方法,开发了一种适用于HfO2铁电薄膜的势函数,将密度泛函理论(DFT)的高精度与分子动力学的高效性相结合,为HfO2铁电薄膜在辐照环境下的位移损伤研究提供了创新性的解决方案。
深度学习与排斥表相结合的深度学习训练方法
这一成果发表在npj Computational Materials 10:270 (2024),题为“A model for studying displacement damage in irradiated HfO2 ferroelectric thin films”。文章的第一通讯单位为西安电子科技大学,材料院研究生张彦军和副教授陈华共同提出了模型的建立方法,通讯作者为周益春教授和陈华副教授。
所建立的模型能够准确预测HfO2中多种晶相的性能,包括PO相(Pca21),T相(P42/nmc), AO相(Pbca), 和M相 (P21/c),更重要的是可以精确描述辐照过程中原子碰撞分离的动态过程,保证了用于预测辐照位移损伤时的准确性。计算出铪原子、三配位氧原子和四配位氧原子的位移阈值能量,分别为57.72 eV、41.93 eV和32.89 eV,这是描述位移损伤的主要特性。
Figure Displacement threshold energy for different incidence directions of PKAs in HfO2. (a) Schematic of the unit cell illustrating the different incidence directions of PKAs, (b) Displacement threshold energy of O3atoms, (c) Displacement threshold energy of O4atoms, and (d) Displacement threshold energy of Hf atoms.
不同入射方向 PKAs 在 HfO2 中的位移阈能
随着初级碰撞原子(PKAs)能量的增加,氧原子PKAs和铪原子PKAs的缺陷形成概率(DFP)逐渐升高,并在高能量时趋于1。在能量低于80.27 eV时,氧PKAs更容易形成点缺陷;而能量高于此阈值时,铪PKAs的缺陷形成概率更高,因为氧PKAs更倾向于形成替换环,一定程度上,抑制了点缺陷的生成。
不同 PKAs能量下的缺陷形成概率(DFP)和缺陷数
该研究对辐照条件下HfO2薄膜中缺陷的形成机制进行了全面分析,为提高HfO2铁电器件在辐照环境中的可靠性提供了重要理论支撑。周益春教授团队的研究不仅丰富了HfO2铁电薄膜的基本物理特性理解,还为新一代高性能铁电器件的抗辐照设计和优化提供了科学依据,这一成果还展现了深度学习与材料科学相结合的巨大潜力。该文近期发表于npj Computational Materials 10: 270 (2024),英文标题与摘要如下,点击左下角“阅读原文”可以自由获取论文PDF。
Deep learning potential model of displacement damage in hafnium oxide ferroelectric films
Hua Chen, Yanjun Zhang,Chao Zhou and Yichun Zhou
A model for studying displacement damage in irradiated HfO2 ferroelectric thin films was developed using deep learning and a repulsive table, combining the accuracy of density functional theory with the efficiency of molecular dynamics. This model accurately predicts the properties of various HfO2 phases, such as PO (Pca21), T (P42/nmc), AO (Pbca), and M (P21/c), and describes the atom collision-separation process during irradiation. The displacement threshold energies for the Hf atoms, three-coordinated O atoms, and four-coordinated O atoms are 57.72, 41.93, and 32.89 eV, respectively. The defect formation probabilities (DFPs) for the O primary knock-on atoms (PKAs) and Hf PKAs increase with energy, reaching 1. Below 80.27 eV, the O PKAs are more likely to form point defects than the Hf PKAs. Above this energy, the Hf PKAs have a higher DFP because the O PKAs form replacement loops more easily, inhibiting the generation of point defects. This study provides a comprehensive understanding of defect formation, which is crucial for increasing the reliability of HfO2 ferroelectric devices under irradiation.
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