The impact of amorphous phases around the holes and at the upper and lower free surfaces on thermal transport in silicon phononic membranes is studied. By means of molecular dynamics and Monte Carlo simulations, we explore the impact of the amorphous phase (oxidation and amorphous silicon), surfaces roughness, and a series of geometric parameters on thermal transport. We show that the crystalline phase drives the phenomena; the two main parameters are (i) the crystalline fraction between two holes and (ii) the crystalline thickness of the membranes. We reveal the hierarchical impact of nanostructurations on the thermal conductivity, namely, from the most resistive to the less resistive: the creation of holes, the amorphous phase around them, and the amorphization of the membranes edges. The surfaces or interfaces perpendicular to the heat flow hinder the thermal conductivity to a much greater extent than those parallel to the heat flow.

中文翻译：

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非晶层对声子晶体热导率的影响

研究了孔周围以及上下自由表面处的非晶相对硅声子膜中热传输的影响。通过分子动力学和蒙特卡洛模拟，我们探索了非晶相（氧化和非晶硅），表面粗糙度以及一系列几何参数对热传递的影响。我们证明了结晶相驱动了这种现象。两个主要参数是（i）两个孔之间的结晶分数和（ii）膜的结晶厚度。我们揭示了纳米结构对热导率的分层影响，即从电阻最大到电阻较小：孔的产生，孔周围的非晶相以及膜边缘的非晶化。