Thermal transport in phononic crystals and the observation of coherent phonon scattering at room temperature
Thermal transport in phononic crystals and the observation of coherent phonon scattering at room temperature
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DOI：
10.1038/ncomms8228
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发表时间：
2015-06-01
影响因子：
16.6
通讯作者：
El-Kady, Ihab
中科院分区：
文献类型：
--
作者：
Alaie, Seyedhamidreza;Goettler, Drew F.;El-Kady, Ihab
在各种多孔结构中，薄硅膜的导热系数都有很大的降低。然而，相干边界散射在这类结构中的作用已经成为一个有争议的问题。本文报道了在特征尺寸最小的硅基中引入空气孔而形成的二维声子晶体中的室温相干声子边界散射的首次实验观测结果。为了从相干边界散射中剥离非相干声子晶体，制备了具有固定最小特征尺寸的声子晶体，仅在晶胞几何上不同。采用悬浮岛法测量了其导热系数。我们引入了一个混合热导模型，该模型考虑了部分相干和部分非相干声子边界散射。我们观察到该模型与实验数据有很好的一致性，结果表明，在室温下发生了显著的相干声子边界散射。
Large reductions in the thermal conductivity of thin silicon membranes have been demonstrated in various porous structures. However, the role of coherent boundary scattering in such structures has become a matter of some debate. Here we report on the first experimental observation of coherent phonon boundary scattering at room temperature in 2D phononic crystals formed by the introduction of air holes in a silicon matrix with minimum feature sizes > 100 nm. To delaminate incoherent from coherent boundary scattering, phononic crystals with a fixed minimum feature size, differing only in unit cell geometry, were fabricated. A suspended island technique was used to measure the thermal conductivity. We introduce a hybrid thermal conductivity model that accounts for partially coherent and partially incoherent phonon boundary scattering. We observe excellent agreement between this model and experimental data, and the results suggest that significant room temperature coherent phonon boundary scattering occurs.