Confinement of phonon propagation in laser deposited tungsten/polycarbonate multilayers
Confinement of phonon propagation in laser deposited tungsten/polycarbonate multilayers
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DOI：
10.1088/1367-2630/18/9/092002
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发表时间：
2016-09-01
影响因子：
3.3
通讯作者：
Krebs, Hans-Ulrich
中科院分区：
文献类型：
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作者：
Doering, Florian;Ulrichs, Henning;Krebs, Hans-Ulrich
W和PC（聚碳酸酯）的纳米多层薄膜由于其组分特性的巨大差异，为各种可能的应用提供了令人着迷的性能，并提供了一个有趣的研究领域，但在低层厚的情况下难以制造。由于两种材料之间存在巨大的声学不匹配，因此这种纳米级结构是新型声子材料的有希望的候选者，其中声子传播被大大减少。在这篇文章中，我们首次证明了用脉冲激光沉积确实可以生长出高质量的W/ pc多层膜。我们分析了聚合物的特性，这取决于用于沉积的激光通量，这使我们能够找到制造高声错配W/PC多层材料的最佳实验条件。用fs泵浦-探针光谱对多层材料进行了分析，结果表明，在ps时间尺度上的声子动力学可以通过结构设计来调整。虽然已经周期的多层材料表现出很强的声子局部化，特别是非周期结构表现出非常低的声子传播特性，使得这种一维层状W/PC纳米结构对新的声子应用很感兴趣。
Nanoscale multilayer thin films of W and PC (Polycarbonate) show, due to the great difference of the components' characteristics, fascinating properties for a variety of possible applications and provide an interesting research field, but are hard to fabricate with low layer thicknesses. Because of the great acoustic mismatch between the two materials, such nanoscale structures are promising candidates for new phononic materials, where phonon propagation is strongly reduced. In this article we show for the first time that W/PC-multilayers can indeed be grown with high quality by pulsed laser deposition. We analyzed the polymer properties depending on the laser fluence used for deposition, which enabled us to find best experimental conditions for the fabrication of high-acoustic-mismatch W/PC multilayers. The multilayers were analyzed by fs pump-probe spectroscopy showing that phonon dynamics on the ps time-scale can strongly be tailored by structural design. While already periodic multilayers exhibit strong phonon localization, especially aperiodic structures present outstandingly low phonon propagation properties making such 1D-layered W/PC nano-structures interesting for new phononic applications.