Department of Physics, University of Southern California, Los Angeles, CA 90089, USA.
Nanotechnology. 2011 Jul 29;22(30):305709. doi: 10.1088/0957-4484/22/30/305709. Epub 2011 Jul 1.
We study the effect of polarized laser annealing on the crystalline structure of individual crystalline-amorphous core-shell silicon nanowires (NWs) using Raman spectroscopy. The crystalline fraction of the annealed spot increases dramatically from 0 to 0.93 with increasing incident laser power. We observe Raman lineshape narrowing and frequency hardening upon laser annealing due to the growth of the crystalline core, which is confirmed by high resolution transmission electron microscopy (HRTEM). The anti-Stokes:Stokes Raman intensity ratio is used to determine the local heating temperature caused by the intense focused laser, which exhibits a strong polarization dependence in Si NWs. The most efficient annealing occurs when the laser polarization is aligned along the axis of the NWs, which results in an amorphous-crystalline interface less than 0.5 µm in length. This paper demonstrates a new approach to control the crystal structure of NWs on the sub-micron length scale.
我们使用拉曼光谱研究了偏振激光退火对单个晶态-非晶态核壳硅纳米线（NWs）晶体结构的影响。随着入射激光功率的增加，退火区域的晶体分数从 0 急剧增加到 0.93。我们观察到由于晶体核的生长，激光退火导致拉曼线宽变窄和频率变硬，这通过高分辨率透射电子显微镜（HRTEM）得到了证实。反斯托克斯：斯托克斯拉曼强度比用于确定由强聚焦激光引起的局部加热温度，在 Si NWs 中表现出强烈的偏振依赖性。当激光偏振方向与 NWs 的轴一致时，退火效果最有效，这导致非晶-晶界面的长度小于 0.5 µm。本文展示了一种在亚微米长度范围内控制 NWs 晶体结构的新方法。
