Saito Y, Motohashi M, Hayazawa N, Kawata S
RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
J Microsc. 2008 Feb;229(Pt 2):217-22. doi: 10.1111/j.1365-2818.2008.01889.x.
Tip-enhanced Raman imaging of strained silicon reveals the property of nanoscale stress imposed on the lattice. Our approach relies on the highly localized excitation provided by a metallized tip. Surface sensitive detections in nanoscale are realized by a reflection-mode configuration combined with 442-nm excitation and a silver-coated silicon nitride tip. The background signals from an underlying silicon germanium layer and a tip are well suppressed. The quantitative stress analysis is made on the basis of the Raman shift of the Si-Si phonon mode. We succeeded in visualizing the localized stress with a spatial resolution down to 25 nm whereas a conventional micro Raman technique provides only a uniform image because of the averaging effect within a diffraction-limited focused spot.
应变硅的针尖增强拉曼成像揭示了施加在晶格上的纳米级应力特性。我们的方法依赖于金属化针尖提供的高度局域化激发。通过结合442纳米激发和镀银氮化硅针尖的反射模式配置，实现了纳米级的表面敏感检测。来自下层硅锗层和针尖的背景信号得到了很好的抑制。基于Si-Si声子模式的拉曼位移进行定量应力分析。我们成功地以低至25纳米的空间分辨率可视化了局部应力，而传统的显微拉曼技术由于在衍射极限聚焦光斑内的平均效应，只能提供均匀的图像。
