Quasi-Ballistic Heat Conduction due to Levy Phonon Flights in Silicon Nanowires
Quasi-Ballistic Heat Conduction due to Levy Phonon Flights in Silicon Nanowires
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DOI：
10.1021/acsnano.8b07597
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发表时间：
2018-12-01
期刊：
影响因子：
17.1
通讯作者：
Nomura, Masahiro
中科院分区：
文献类型：
--
作者：
Anufriev, Roman;Gluchko, Sergei;Nomura, Masahiro
硅基微电子的未来取决于散热问题的解决。解决方案可能在于一种被称为弹道热传导的纳米级现象，即在不加热导体的情况下进行热传导。然而，在实验上证明这一现象的尝试是有争议的，而且很少，而它在受限纳米结构中的机制还没有完全被理解。在这里，我们实验演示了硅纳米线的准弹道导热。我们发现，在较低的温度下，短原子核的弹道性质最强，但随着原子核长度或温度的增加，弹道效应减弱。然而，即使在室温下，准弹道导热在短时间内仍然可见。为了更好地理解这一现象，我们探索了声子飞行的方向和长度。我们的实验和模拟表明，NWS中的准弹道声子输运本质上是在NW边界之间短飞行和沿NW长弹道跃迁的Levy行走。因此，我们得出结论，即使在室温下，硅中也存在足够小的纳米结构中的弹道导热，并可能改善硅基微电子的热管理。
Future of silicon-based microelectronics depends on solving the heat dissipation problem. A solution may lie in a nanoscale phenomenon known as ballistic heat conduction, which implies conduction of heat without heating the conductor. However, attempts to demonstrate this phenomenon experimentally are controversial and scarce, whereas its mechanism in confined nanostructures is yet to be fully understood. Here, we experimentally demonstrate quasi ballistic heat conduction in silicon nanowires (NWs). We show that the ballisticity is the strongest in short NWs at low temperatures but weakens as the NW length or temperature is increased. Yet, even at room temperature, quasi-ballistic heat conduction remains visible in short NWs. To better understand this phenomenon, we probe directions and lengths of phonon flights. Our experiments and simulations show that the quasi-ballistic phonon transport in NWs is essentially the Levy walk with short flights between the NW boundaries and long ballistic leaps along the NW. Thus, we conclude that ballistic heat conduction is present in silicon even at room temperature in sufficiently small nanostructures and may yet improve thermal management in silicon-based microelectronics.