Research on thermal transport mechanism of amorphous hafnia based on quasi-harmonic Green-Kubo theory combined with hydrodynamic extrapolation method

XF Zhu and JS Sun and YC Xiong and SH Li and XJ Liu, ACTA PHYSICA SINICA, 74, 116302 (2025).

DOI: 10.7498/aps.74.20250350

Amorphous hafnia (alpha-HfO2) has attracted considerable attention due to its excellent dielectric properties and broad applicability in the electronic industry. Considering that the self-heating is becoming the bottleneck for the performance and reliability of microelectronic devices, it is necessary to clarify the thermal transport mechanism in alpha-HfO2. The microstructures of alpha-HfO2 can be significantly changed during the fabrication process, whose effects on thermal transport remain to be revealed. Here, we conduct a comprehensive investigation of thermal transport in alpha-HfO2 based on the quasi- harmonic Green-Kubo (QHGK) theory combined with hydrodynamic extrapolation. The calculation scheme fully considers the contributions from low-frequency vibrational modes, overcoming the drawbacks of finite size in the single QHGK method and molecular dynamics simulation. It is found that the thermal conductivity (k) of alpha-HfO2 is weakly related to its degree of order. The amorphous structures with slower quenching speed and higher degree of order have higher thermal conductivities due to their slightly larger relaxation times. Modal analyses show that the mid-and low-frequency vibrational modes have significant contributions to thermal transport in alpha-HfO2, which is the main reason for the underestimation of the kin other methods. Based on the anharmonic dynamic structure factor, we further separate the contributions of two fundamental heat carriers in amorphous materials: propagons and diffusons. It is found that diffusons dominate the kin all alpha-HfO2 structures. Nevertheless, the contribution of the propagons is non- negligible, accounting for more than 20% and increasing with the degree of structural ordering. This study provides new insights into the microscopic mechanisms and guidance for manipulating thermal transport in alpha-HfO2.

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