Nanoscale thermal conductivity spectroscopy by using gold nano-islands heat absorbers
Nanoscale thermal conductivity spectroscopy by using gold nano-islands heat absorbers
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DOI：
10.1063/1.4913311
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发表时间：
2015-02
影响因子：
4
通讯作者：
T. Oyake;M. Sakata;J. Shiomi
中科院分区：
文献类型：
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作者：
T. Oyake;M. Sakata;J. Shiomi
利用金纳米岛的时域热反射率，建立了一种几十纳米尺度的准弹道热输运测量技术。通过在衬底表面形成的金纳米岛的瞬态温度变化，获得了准弹道热输运对透明衬底（熔融石英、晶体石英和蓝宝石）的视导热系数的抑制，并通过改变金纳米岛的尺寸量化了几十纳米范围内导热系数的尺寸效应。此外，利用玻尔兹曼输运方程的解拟合测量的尺寸效应，得到了衬底声子的特征平均自由程。结果表明，当晶型尺寸减小到60 nm以下时，室温下熔融石英的尺寸效应显著。
A measurement technique of quasi-ballistic thermal transport in tens of nanometers has been developed by using time-domain thermoreflectance of gold nano-islands. The suppressed apparent thermal conductivity of transparent substrates (fused quartz, crystal quartz, and sapphire) due to quasi-ballistic thermal transport is obtained through the transient temperature change of the gold nano-islands formed on the substrate surface, and the size effect of thermal conductivity in the range of tens of nanometers is quantified by varying the gold nano-island sizes. Furthermore, characteristic phonon mean free paths of the substrates were obtained by fitting the measured size effect with a solution of a Boltzmann transport equation. The results identify that the size-effect of amorphous fused quartz at room temperature becomes significant when the size is reduced below 60 nm.