Size and interface effects on thermal conductivity of superlattices and periodic thin-film structures
Size and interface effects on thermal conductivity of superlattices and periodic thin-film structures
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DOI：
10.1115/1.2824212
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发表时间：
1997-05-01
影响因子：
--
通讯作者：
Chen, G
中科院分区：
文献类型：
--
作者：
Chen, G
由极薄薄膜交替层组成的超晶格通常表现出强烈的量子尺寸效应，这些效应已被用于改进传统器件和开发新器件。这些结构中的界面也通过热载体的反射和透射影响其热物理性质。本文基于玻尔兹曼输运方程建立了平行方向周期性薄膜结构的有效热导率模型。不同的界面条件，包括镜面反射，漫反射，部分镜面反射和部分漫反射接口，被认为是。从部分镜面和部分漫反射界面散射模型得到的结果与GaAs/AlAs超晶格的实验数据符合得很好。研究表明，原子尺度的界面粗糙度是导致超晶格热导率降低的主要原因。这项工作还表明，通过控制界面粗糙度，由具有高热导率的块体材料制成的超晶格的有效热导率可以降低到与非晶材料相当的水平，同时保持高电导率。这一建议为寻找高效热电材料开辟了新的可能性。
Superlattices consisting of alternating layers of extremely thin films often demonstrate strong quantum size effects that have been utilized to improve conventional devices and develop new ones. The interfaces in these structures also affect their thermophysical properties through reflection and transmission of heat carriers. This work develops models on the effective thermal conductivity of periodic thin-film structures in the parallel direction based on the Boltzmann transport equation. Different interface conditions including specular, diffuse, and partially specular and partially diffuse interfaces, are considered. Results obtained from the partially specular and partially diffuse interface scattering model are in good agreement with experimental data on GaAs/AlAs superlattices. The study shows that the atomic scale interface roughness is the major cause for the measured reduction in the superlattice thermal conductivity. This work also suggests that by controlling interface roughness, the effective thermal conductivity of superlattices made of bulk materials with high thermal conductivities can be reduced to a level comparable to those of amorphous materials, while maintaining high electrical conductivities. This suggestion opens new possibilities in the search of high efficiency thermoelectric materials.