As electronic devices shrink down to their ultimate limit, the fundamental understanding of interfacial thermal transport becomes essential in thermal management. However, a comprehensive understanding of phonon transport mechanisms that drive interfacial thermal transport is still under development. The thermal transport across interfaces can be strongly affected by factors such as crystalline structure, surface roughness, chemical diffusion, etc. These complications lead to a significant quantitative uncertainty between experimentally measured thermal boundary conductance (TBC) across real material interfaces and theoretically calculated TBCs that are often predicted on structurally and/or chemically ideal interfaces. In this paper, we report on the thermal conductance across interfaces between various epitaxially grown metal films (Co, Ru, and Al) and $c$-plane sapphire substrates via time-domain thermoreflectance over the temperature range of ∼80 to ∼500 K. The room-temperature interface conductances of Al/sapphire, Co/sapphire, and Ru/sapphire are all $\sim 350\mathrm{MW}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ despite the phonon spectra differences among the metals. We compare our results to predictions of TBC using atomistic Green's function calculations and the modal nonequilibrium Landauer method with transmission from the diffuse mismatch model. We found a consistent quantitative agreement between the experimentally measured TBCs and the predictions using the modal nonequilibrium Landauer model for the $\mathrm{Al}/{\mathrm{Al}}_2{\mathrm{O}}_3$, $\mathrm{Co}/{\mathrm{Al}}_2{\mathrm{O}}_3$, and $\mathrm{Ru}/{\mathrm{Al}}_2{\mathrm{O}}_3$ interfaces. This result suggests that interfacial elastic phonon thermal transport dominates TBC for the various epitaxial metal/sapphire combinations of interest in this work, while other mechanisms are negligible.

中文翻译：

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外延金属/蓝宝石界面上的热边界电导

随着电子设备的缩小到极限，对热传导的基本了解变得至关重要。但是，对驱动界面热传输的声子传输机制的全面理解仍在发展中。跨界面的热传输会受到诸如晶体结构，表面粗糙度，化学扩散等因素的强烈影响。这些复杂性导致跨真实材料界面的实验测量的热边界电导（TBC）与理论计算的TBC之间存在显着的定量不确定性。通常在结构和/或化学上理想的界面上进行预测。在本文中，我们报告了各种外延生长的金属膜（Co，Ru，$C$在约80至约500 K的温度范围内通过时域热反射形成平面蓝宝石衬底。Al/蓝宝石，Co /蓝宝石和Ru /蓝宝石的室温界面电导均为 $〜350\mathrm{兆瓦}{\mathrm{米}}^{-\mathrm{1个}}{\mathrm{ķ}}^{-\mathrm{1个}}$尽管金属之间的声子光谱差异。我们将我们的结果与使用原子性格林函数计算和模态非平衡Landauer方法的TBC预测进行比较，并通过扩散失配模型进行传输。我们发现实验测量的TBC与使用模态非平衡Landauer模型进行的预测之间的一致性定量一致性$铝/{铝}_2{\mathrm{Ø}}_3$， $\mathrm{有限公司}/{铝}_2{\mathrm{Ø}}_3$和 $茹/{铝}_2{\mathrm{Ø}}_3$接口。该结果表明，在这项工作中，界面弹性声子的热输运控制了各种感兴趣的外延金属/蓝宝石组合的TBC，而其他机理则可以忽略不计。