External electric field driving the ultra-low thermal conductivity of silicene
External electric field driving the ultra-low thermal conductivity of silicene
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DOI：
10.1039/c7nr01596h
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发表时间：
2017-06-07
期刊：
影响因子：
6.7
通讯作者：
Hu, Ming
中科院分区：
文献类型：
--
作者：
Qin, Guangzhao;Qin, Zhenzhen;Hu, Ming
热传输的操纵是在不断增长的需求，因为热传递在广泛的实际应用中起着关键作用，如纳米电子学中的有效散热和固态热电器件中的热传导阻碍。众所周知，半导体和绝缘体（声子）中的热输运可以通过结构工程或材料加工来有效地调制。然而，几乎所有现有的方法都涉及改变材料的原始原子结构，这将由于不可逆的结构变化或有限的热导率可调性而受到阻碍。基于声子行为与原子间静电相互作用之间的内在联系，我们全面研究了外加电场对晶格热导率（k）的影响.以二维硅为模型，我们证明了在电场（E-z = 0.5VA（-1））作用下，结果表明，硅烯的介电常数可降至0.091 W m（-1）K-1，比无电场时的介电常数（19.21 W m（-1）K-1）低两个数量级以上，甚至可与最好的绝热材料相媲美。从观察电子结构中获得了基本的见解。在外加电场作用下，由于电荷密度的重新分布而产生的屏蔽势，硅原子间的相互作用被重正化，导致声子重正化，并通过电子-声子耦合对声子非谐性进行调制。我们的研究为在不改变原子结构的情况下稳健地调谐材料中的声子输运铺平了道路，并将对新兴应用产生重大影响，如热管理，纳米电子学和热电学。
The manipulation of thermal transport is in increasing demand as heat transfer plays a critical role in a wide range of practical applications, such as efficient heat dissipation in nanoelectronics and heat conduction hindering in solid-state thermoelectrics. It is well established that the thermal transport in semiconductors and insulators (phonons) can be effectively modulated by structure engineering or materials processing. However, almost all the existing approaches involve altering the original atomic structure of materials, which would be hindered due to either irreversible structure change or limited tunability of thermal conductivity. Motivated by the inherent relationship between phonon behavior and interatomic electrostatic interaction, we comprehensively investigate the effect of external electric field, a widely used gating technique in modern electronics, on the lattice thermal conductivity (k). Taking two-dimensional silicon (silicene) as a model, we demonstrate that by applying an electric field (E-z = 0.5 V A(-1)) the. of silicene can be reduced to a record low value of 0.091 W m(-1) K-1, which is more than two orders of magnitude lower than that without an electric field (19.21 W m(1) K-1) and is even comparable to that of the best thermal insulation materials. Fundamental insights are gained from observing the electronic structures. With an electric field applied, due to the screened potential resulting from the redistributed charge density, the interactions between silicon atoms are renormalized, leading to phonon renormalization and the modulation of phonon anharmonicity through electron-phonon coupling. Our study paves the way for robustly tuning phonon transport in materials without altering the atomic structure, and would have significant impact on emerging applications, such as thermal management, nanoelectronics and thermoelectrics.