一维脉冲中非局域声子热输运
Nonlocal Phonon Heat Transport Seen in 1-d Pulses
摘要：
声子是半导体器件中的主要热载体。在小型设备中，热量不是由局部温度梯度驱动的，而是由局部热量输入和去除点驱动的。这使理论模型复杂化。从初始局域脉冲的振动能量的传播的研究提供了深入了解非局域声子热输运。我们报告模拟脉冲在一维传播。一维情况下有棘手的异常，但提供了最简单的图片演变从最初的弹道到较长时间的扩散传播。我们的研究结果显示了令人惊讶的细节，如不同的结果从不同的定义原子的本地能源，并未能表现出纯扩散在很长一段时间。本文应用玻尔兹曼声子气体理论，包括外加能量的引入，解决了这一固有的非定域问题。采用杂质散射的弛豫时间近似的解与模拟结果并不完全一致。
英文摘要：
Phonons are the main heat carriers in semiconductor devices. In small devices, heat is not driven by a local temperature gradient, but by local points of heat input and removal. This complicates theoretical modeling. Study of the propagation of vibrational energy from an initial localized pulse provides insight into nonlocal phonon heat transport. We report simulations of pulse propagation in one dimension. The 1d case has tricky anomalies, but provides the simplest pictures of the evolution from initially ballistic toward longer time diffusive propagation. Our results show surprising details, such as diverse results from different definitions of atomistic local energy, and failure to exhibit pure diffusion at long times. Boltzmann phonon gas theory, including external energy insertion, is applied to this inherentlytime-dependent and nonlocal problem. The solution, using relaxation time approximation for impurity scattering, does not closely agree with the simulated results.
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