Anisotropic thermal conductivity in 2D tellurium
Anisotropic thermal conductivity in 2D tellurium
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DOI：
10.1088/2053-1583/ab4eee
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发表时间：
2020-01-01
期刊：
影响因子：
5.5
通讯作者：
Xu, Xianfan
中科院分区：
文献类型：
--
作者：
Huang, Shouyuan;Segovia, Mauricio;Xu, Xianfan
二维碲（2D-Te）材料具有高迁移率、环境稳定性、热电功率因数高、易于批量生产等优点，在电子学、光电子学、热电学等领域具有广阔的应用前景。这些2D-Te薄膜具有独特的原子结构：Te原子形成三角形螺旋链，然后通过货车德瓦尔斯力堆叠成六方晶格，从而产生独特的输运行为。在这里，我们报告的各向异性热导率悬浮2D-Te薄膜测量显微拉曼测温和时域热反射（TDTR）的方法。的面内沿链和跨链的热导率被发现是约2.5和1.7 W m（？1)K-？1，分别为较厚的薄膜（>100？nm），分别为1.6和0.64 W m（？）1)K-？1对于较薄的膜（1.3对于所研究的所有膜。的跨平面（也跨链）的热导率被发现是约0.8至1.2 W m（？1)K-？对于较厚的膜，由于薄膜边界的较强抑制，沿面内横链方向的比沿着略低。理论模拟表明，各向异性主要来源于各向异性声子色散。Te中的长平均自由程声子也被边界散射强烈抑制。大部分材料的各向异性热导率的大幅降低使其成为最佳的单元件热电材料，并使室温下的热电发电或冷却装置成为可能。我们的研究结果也提供了关键的信息，2D-Te电子器件的热管理。
Two-dimensional tellurium (2D-Te) has been recently synthesized and shown potential in electronics, optoelectronics, and thermoelectric applications, with the merits of high mobility, environmental stability, high thermoelectric power-factor, and simplicity of mass production. These 2D-Te films have unique atomic structures: the Te atoms form trigonal helical chains and are then stacked into hexagonal lattice by van der Waals force, which brings up distinctive transport behaviors. Here we report anisotropic thermal conductivity of suspended 2D-Te films measured by micro-Raman thermometry and the time-domain thermal reflectance (TDTR) method. The in-plane along-chain and cross-chain thermal conductivities are found to be around 2.5 and 1.7 W m(?1) K-?1, respectively, for thicker films (>100?nm), and reduced to 1.6 and 0.64 W m(?1) K-?1 for the thinner films (1.3 for all the films studied. The cross-plane (also across-chain) thermal conductivity is found to be around 0.8 to 1.2 W m(?1) K-?1 for thicker films, slightly lower than that along the in-plane across-chain direction due to the stronger suppression by the thin film boundary. Theoretical modeling reveals that the anisotropy mainly originates from anisotropic phonon dispersion. The long mean-free-path phonons in Te are also shown to be strongly suppressed by boundary scattering. The large reduction of anisotropic thermal conductivity from the bulk makes it the best single-element thermoelectric material and enables potential thermoelectric generation or cooling devices at room temperature. Our results also provide critical information for thermal management of 2D-Te electronic devices.