Thermal Boundary Conductance Across Heteroepitaxial ZnO/GaN Interfaces: Assessment of the Phonon Gas Model
Thermal Boundary Conductance Across Heteroepitaxial ZnO/GaN Interfaces: Assessment of the Phonon Gas Model
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DOI：
10.1021/acs.nanolett.8b02837
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发表时间：
2018-12-01
期刊：
影响因子：
10.8
通讯作者：
Hopkins, Patrick E.
中科院分区：
文献类型：
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作者：
Gaskins, John T.;Kotsonis, George;Hopkins, Patrick E.
我们提出了实验测量的热边界电导率（TBC）从78-500 K跨越孤立的异质外延生长ZnO薄膜在GaN衬底。这些数据提供了对驱动声子气体模型的基本假设的评估，例如扩散失配模型（DMM）和用于预测TBC的原子格林函数（AGF）形式。与之前的实验数据相比，我们的测量结果表明，TBC可以受到界面一侧材料的长波长的区域中心模式的影响，而不是DMM中假设的“振动不匹配”概念；这种分歧在高温下更为明显。在室温下，我们测量到ZnO/GaN的TBC为490[+150，-110]MW m(-2) K-1。DMM和AGF之间的分歧以及高温下的实验数据表明，其他类型的模态的贡献不可忽略，这些模态在这些基于谐波的形式的基本假设中没有考虑到，这可能依赖于非调和性。鉴于这些ZnO/GaN界面的高质量，这些结果提供了一个宝贵的、关键的和定量的评估，用于预测声子跨界面TBC的计算方法的当前状态的假设的准确性。
We present experimental measurements of the thermal boundary conductance (TBC) from 78-500 K across isolated heteroepitaxially grown ZnO films on GaN substrates. This data provides an assessment of the underlying assumptions driving phonon gas-based models, such as the diffuse mismatch model (DMM), and atomistic Green's function (AGF) formalisms used to predict TBC. Our measurements, when compared to previous experimental data, suggest that TBC can be influenced by long wavelength, zone center modes in a material on one side of the interface as opposed to the "vibrational mismatch" concept assumed in the DMM; this disagreement is pronounced at high temperatures. At room temperature, we measure the ZnO/GaN TBC as 490[+150,-110] MW m(-2) K-1. The disagreement among the DMM and AGF, and the experimental data at elevated temperatures, suggests a non-negligible contribution from other types of modes that are not accounted for in the fundamental assumptions of these harmonic based formalisms, which may rely on anharmonicity. Given the high quality of these ZnO/GaN interfaces, these results provide an invaluable, critical, and quantitative assessment of the accuracy of assumptions in the current state of the art computational approaches used to predict phonon TBC across interfaces.