High contrast scanning nano‐Raman spectroscopy of silicon

Abstract

We have demonstrated that scanning nano-Raman spectroscopy (SNRS), generally known as tip-enhanced Raman spectroscopy (TERS), with side illumination optics can be effectively used for analysis of siliconbased structures at the nanoscale. Even though the side illumination optics has disadvantages such as difficulties in optical alignment and shadowing by the tip, it has the critical advantage that it may be used for the analysis of nontransparent samples. A key criterion for making SNRS effective for imaging Si samples is the optimization of the contrast between near-field and far-field (background) Raman signals. This has been achieved by optimizing the beam polarization, resulting in an order of magnitude improvement in the contrast. We estimate the lateral resolution of our Raman images to be ∼ 20 nm.

Detection of Carbon Nanotubes using Tip-Enhanced Raman Spectroscopy

“…It may be used in inspections for stress distribution and fission process in nanometer scale (Zhu et al, 2007a(Zhu et al, , 2007bGeorgi et al, 2007). The polarization control techniques may be used to reduce the far-field background to improve the contrast (Lee et al, 2007).…”

“…Another issue concerning AFM-TERS tips is that the Raman signal of the inner material of the TERS tips (Si or Si3N4) is also being enhanced and exists as the noise. Especially in the research on semi-conductor materials, this issue should be pay closer attention to (Lee et al, 2007). The preparation of STM-TERS tips is comparatively mature.…”

“…Up to now, it has been applied to dye molecule detection (Steidtner & Pettinger, 2008;W. H. Zhang et al, 2007), semi-conductor material determination (Sun et al, 2003;Lee et al, 2007;Saito et al, 2008;Sun & Shen, 2001) , biological specimen identification (Anderson et al, 2003;Bailo & Deckert, 2008), and nanao-material characterization (Hayazawa et al, 2000;Hartschuh et al, 2003;J. J. Wang et al, 2005;Qian et al, 2006).…”

“…By correspondingly analyzing the two images, the specific recognition of the feature distribution can be realized. With the development in recent years, TERS has been applied to the characterization of nano-materials (Hayazawa et al, 2003;Huihong et al, 2006;Hartschuh et al, 2003), biological specimens (Anderson et al, 2003;Bailo & Deckert, 2008), dye molecules (Hayazawa et al, 2000;Pettinger et al, 2004;Watanabe et al, 2005), and semiconductor materials (Sun et al, 2003;Lee et al, 2007;Saito et al, 2008;Sun & Shen, 2001). In January 2008, the topic meeting, entitled as "Tip Enhanced Raman and Fluorescence Spectroscopy (TERFS): Challenges and Opportunities", was held in the National Physical Laboratory (NPL), London，Britain.…”

Raman spectroscopy of nanostructures and nanosized materials

“…Note that the investigated sample and the intermediate phases presented above 26 are completely opposite among nanostructured materials: here, nonstoichiometry introduces nanodisordering in a reference crystal, whereas intermediate phases reflect a nanostructuring of amorphous systems. 42 report on the TERS of strained silicon (the same topic as in the review by Hayazawa et al 21 ). Raman mapping at high resolution (¾20 nm) was achieved thanks to a careful optimization of the beam polarization (to get the best near-field to far-field contrast possible).…”