Sahoo Satyaprakash, Dhara S, Mahadevan S, Arora A K
Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India.
J Nanosci Nanotechnol. 2009 Sep;9(9):5604-7. doi: 10.1166/jnn.2009.1141.
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.
利用拉曼光谱对通过离子束注入合成的嵌入蓝宝石中的硅纳米团簇中的受限声子和光学声子进行了研究。在低拉曼位移处发现的l = 0和l = 2受限声子，使用复频模型进行了分析，纳米颗粒的尺寸估计为4纳米和6纳米。对于受限光学声子，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与尺寸相关的压缩应力。计算得到的受压纳米颗粒的拉曼线形状与数据拟合良好。使用复频模型获得的硅纳米颗粒尺寸与根据受限光学声子线形状拟合估计的尺寸以及从X射线衍射和透射电子显微镜获得的尺寸一致。
