应力作用下硅纳米团簇中的声子禁闭
Phonon Confinement in Stressed Silicon Nanocluster
摘要：
利用拉曼光谱研究了离子束注入法合成的蓝宝石中硅纳米团簇中的声子和声子。使用复频率模型分析了在低拉曼位移下发现的l = 0和l = 2受限声学声子，并估计纳米颗粒的尺寸为4和6 nm。对于受限的光学声子，与预期的红移相反，拉曼线形状显示出显著的蓝移，这归因于纳米颗粒中的尺寸依赖的压缩应力。应力纳米颗粒的计算拉曼线形状与数据拟合良好。利用复频率模型得到的Si纳米颗粒的尺寸与由受限光学声子线形状拟合估计的尺寸以及由X射线衍射和TEM发现的尺寸一致。
英文摘要：
Confined acoustic and optical phonons in Si nanoclusters embedded in sapphire, synthesized using ion-beam implantation are investigated using Raman spectroscopy. The l = 0 and l = 2 confined acoustic phonons, found at low Raman shift, are analyzed using complex frequency model and the size of the nanoparticles are estimated as 4 and 6 nm. For the confined optical phonon, in contrast to expected red shift, the Raman line shape shows a substantial blue shift, which is attributed to size dependent compressive stress in the nanoparticles. The calculated Raman line shape for the stressed nanoparticles fits well to data. The sizes of Si nanoparticles obtained using complex frequency model are consistent with the size estimated from the fitting of confined optical phonon line shapes and those found from X-ray diffraction and TEM.
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