Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity
Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity
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DOI：
10.1063/1.4905607
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发表时间：
2015-01-14
影响因子：
3.2
通讯作者：
Wang, Xinwei
中科院分区：
文献类型：
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作者：
Cheng, Zhe;Xu, Zaoli;Wang, Xinwei
通过研究温度依赖行为（300 K下降到43 K）的电子热导率（κ）在3.2 nm薄的Ir膜，我们量化的极端有限的缺陷电子散射和隔离的固有声子电子散射是由体Ir共享。在低于50 K的低温下，薄膜的kappa比体相铱的kappa降低了近两个数量级，薄膜的偏导kappa/偏导T > 0，而体相铱的偏导kappa/偏导T < 0。我们引入了一个统一的热阻率（θ = T/kappa）来解释这些完全不同的kappa类似于T的关系。发现薄膜和体Ir具有非常相似的Theta，其趋势与T相似，但它们在0 K极限下具有不同的剩余部分（Theta（0））：体Ir的Theta（0）与0相似，而薄膜的Theta（0）= 5.5m.K-2/W。Ir薄膜和体Ir具有非常接近的偏导数θ/偏导数T（75-290 K）：薄膜为6.33 × 10（-3）m K/W，体Ir为7.62 × 10（-3）m K/W，这有力地证实了它们中相似的声子-电子散射。因此，残余热阻率提供了一种前所未有的方式来定量评估缺陷电子散射（θ（0））在热传导。此外，界面的热导率在晶界被发现大于Al/Cu界面，其值与温度成正比，很大程度上是由于电子的比热。一个统一的界面热导也被定义和坚定地证明了这种关系。此外，电子反射系数被发现是大的（88%），几乎与温度无关。(C)2015 AIP Publishing LLC.
By studying the temperature-dependent behavior (300 K down to 43 K) of electron thermal conductivity (kappa) in a 3.2 nm-thin Ir film, we quantify the extremely confined defect-electron scatterings and isolate the intrinsic phonon-electron scattering that is shared by the bulk Ir. At low temperatures below 50 K, kappa of the film has almost two orders of magnitude reduction from that of bulk Ir. The film has partial derivative kappa/partial derivative T > 0, while the bulk Ir has partial derivative kappa/partial derivative T < 0. We introduce a unified thermal resistivity (Theta = T/kappa) to interpret these completely different kappa similar to T relations. It is found that the film and the bulk Ir share a very similar Theta similar to T trend, while they have a different residual part (Theta(0)) at 0K limit: Theta(0) similar to 0 for the bulk Ir, and Theta(0) = 5.5m.K-2/W for the film. The Ir film and the bulk Ir have very close partial derivative Theta/partial derivative T (75-290 K): 6.33 x 10(-3) m K/W for the film and 7.62 x 10(-3) m K/W for the bulk Ir. This strongly confirms the similar phonon-electron scattering in them. Therefore, the residual thermal resistivity provides an unprecedented way to quantitatively evaluating defect-electron scattering (Theta(0)) in heat conduction. Moreover, the interfacial thermal conductance across the grain boundaries is found larger than that of Al/Cu interface, and its value is proportional to temperature, largely due to the electron's specific heat. A unified interfacial thermal conductance is also defined and firmly proves this relation. Additionally, the electron reflection coefficient is found to be large (88%) and almost temperature independent. (C) 2015 AIP Publishing LLC.