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首页> 外文期刊>Physical review >Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices
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Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices

机译:(Ti,W)N /(Al,Sc)N金属/半导体超晶格的横断面热导率

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摘要

Reduction of cross-plane thermal conductivity and understanding of the mechanisms of heat transport in nanostructured metal/semiconductor superlattices are crucial for their potential applications in thermoelectric and thermionic energy conversion devices, thermal management systems, and thermal barrier coatings. We have developed epitaxial (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices with periodicity ranging from 1 nm to 240 nm that show significantly lower thermal conductivity compared to the parent TiN/(Al,Sc)N superlattice system. The (Ti,W)N/(Al,Sc)N superlattices grow with [001] orientation on the MgO(001) substrates with well-defined coherent layers and are nominally single crystalline with low densities of extended defects. Cross-plane thermal conductivity (measured by time-domain thermoreflectance) decreases with an increase in the superlattice interface density in a manner that is consistent with incoherent phonon boundary scattering. Thermal conductivity values saturate at 1.7Wm~(-1) K~(-1) for short superlattice periods possibly due to a delicate balance between long-wavelength coherent phonon modes and incoherent phonon scattering from heavy tungsten atomic sites and superlattice interfaces. First-principles density functional perturbation theory based calculations are performed to model the vibrational spectrum of the individual component materials, and transport models are used to explain the interface thermal conductance across the (Ti,W)N/(Al,Sc)N interfaces as a function of periodicity. The long-wavelength coherent phonon modes are expected to play a dominant role in the thermal transport properties of the short-period superlattices. Our analysis of the thermal transport properties of (Ti,W)N/( Al,Sc)N metal/semiconductor superlattices addresses fundamental questions about heat transport in multilayer materials.
机译:降低横断面热导率并了解纳米结构金属/半导体超晶格中的热传输机理,对于其在热电和热电子能量转换设备,热管理系统和热障涂层中的潜在应用至关重要。我们已经开发出周期为1 nm至240 nm的外延(Ti,W)N /(Al,Sc)N金属/半导体超晶格,其热导率比母体TiN /(Al,Sc)N超晶格系统低得多。 (Ti,W)N /(Al,Sc)N超晶格在具有明确定义的相干层的MgO(001)衬底上以[001]取向生长,并且名义上是单晶,具有低密度的扩展缺陷。横断面热导率(通过时域热反射率测量)随超晶格界面密度的增加而降低,其方式与非相干声子边界散射一致。在短超晶格周期内,热导率值会在1.7Wm〜(-1)K〜(-1)处饱和,这可能是由于长波长相干声子模与重钨原子位点和超晶格界面的非相干声子散射之间的微妙平衡所致。进行基于第一原理密度泛函微扰理论的计算以对单个成分材料的振动谱进行建模,并使用传输模型来解释跨(Ti,W)N /(Al,Sc)N界面的界面热导,周期性的函数。长波长相干声子模式有望在短周期超晶格的热输运性质中发挥主导作用。我们对(Ti,W)N /(Al,Sc)N金属/半导体超晶格的热传输特性的分析解决了有关多层材料中热传输的基本问题。

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  • 来源
    《Physical review》 |2016年第4期|045311.1-045311.11|共11页
  • 作者单位

    School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA,Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA 94720, USA;

    School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA;

    School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA;

    School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA;

    Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping, Sweden;

    Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping, Sweden;

    School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA;

    Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping, Sweden;

    School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA;

    School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA;

    Bradley Department of Electrical and Computer Engineering and Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA;

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