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非晶态材料二氧化铪在微电子器件中具有广泛应用, 理解其微观导热机制对于提升电子器件的性能和可靠性至关重要. 以往的研究大多基于分子动力学和单一准简谐格林-久保方法, 难以准确考虑低频振动模式的导热贡献. 本文基于准简谐格林-久保理论, 结合流体动力学外推法, 对不同有序度的非晶二氧化铪结构的热输运机制进行全面研究. 该方法可有效克服单一准简谐格林-久保方法中的有限尺寸问题. 理论预测表明, 非晶二氧化铪的热导率与微观结构有序度呈现弱相关性. 基于模态分析表明, 中低频振动模式对热导率具有显著贡献, 是单一准简谐格林-久保方法低估非晶二氧化铪热导率的主要原因. 同时, 本文基于非谐动态结构因子分离了传播子和扩散子对非晶二氧化铪导热的贡献, 计算表明扩散子在所有非晶二氧化铪结构导热中均占据主导作用. 然而, 传播子的导热贡献仍不可忽略, 其占比可高达20%以上, 且随着有序度的增大而增大.
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关键词:
- 热导率 /
- 非晶二氧化铪 /
- 准简谐格林-久保理论 /
- 流体力学外推方法
The amorphous hafnia has a wide range of applications in microelectronic devices, and understanding its microscopic thermal transport mechanism is crucial for improving the performance and reliability of electronic devices. Most previous studies are based on molecular dynamics and the single quasi-harmonic Green-Kubo method, which makes it difficult to accurately consider the contribution of low-frequency vibrational modes to thermal conductivity. In this paper, based on the quasi-harmonic Green-Kubo method combined with hydrodynamic extrapolation, the heat transport mechanism of amorphous hafnia structures with different degrees of ordering is comprehensively investigated. The method effectively overcomes the finite size issue inherent in the single quasi-harmonic Green-Kubo method. Theoretical predictions show that the thermal conductivity of amorphous hafnia exhibits a weak correlation with the degree of microstructural ordering. Modal analysis reveals that low- and mid-frequency vibrational modes significantly contribute to thermal conductivity, which is the main reason for the underestimation of the thermal conductivity of amorphous hafnia in the single quasi-harmonic Green-Kubo method. Furthermore, this paper separates the contributions of propagons and diffusons to the thermal conductivity of amorphous hafnia using the anharmonic dynamic structure factor, revealing that diffusons dominate the thermal conductivity of all amorphous hafnia structures. However, the contribution of the propagons to thermal conductivity remains significant, reaching over 20% and increasing with the degree of ordering.-
Keywords:
- thermal conductivity /
- amorphous hafnia /
- quasi-harmonic Green-Kubo theory /
- hydrodynamic extrapolation method
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