Lifetimes of Confined Acoustic Phonons in Ultrathin Silicon Membranes
Lifetimes of Confined Acoustic Phonons in Ultrathin Silicon Membranes
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DOI：
10.1103/physrevlett.110.095503
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发表时间：
2013-02-26
影响因子：
8.6
通讯作者：
Sotomayor Torres, C. M.
中科院分区：
文献类型：
--
作者：
Cuffe, J.;Ristow, O.;Sotomayor Torres, C. M.
我们研究了超薄独立硅膜中频率高达500 GHz的相干声子模式的弛豫。利用非同步光学采样的超快泵浦-探针技术，我们观察到随着膜厚度从194 nm减小到8 nm，一阶扩张模式的衰减时间从4.7 ns显著减小到5 ps。实验结果与考虑声子-声子内在相互作用和外在表面粗糙度散射（包括波长相关的镜面散射）的理论进行了比较。我们的研究结果为理解纳米机械谐振器和纳米结构中的热输运的一些局限性提供了见解。DOI: 10.1103 / PhysRevLett.110.095503
We study the relaxation of coherent acoustic phonon modes with frequencies up to 500 GHz in ultrathin free-standing silicon membranes. Using an ultrafast pump-probe technique of asynchronous optical sampling, we observe that the decay time of the first-order dilatational mode decreases significantly from similar to 4.7 ns to 5 ps with decreasing membrane thickness from similar to 194 to 8 nm. The experimental results are compared with theories considering both intrinsic phonon-phonon interactions and extrinsic surface roughness scattering including a wavelength-dependent specularity. Our results provide insight to understand some of the limits of nanomechanical resonators and thermal transport in nanostructures. DOI: 10.1103/PhysRevLett.110.095503