Study of Enhanced Raman Scattering with Grating
Date Issued
2007
Date
2007
Author(s)
Lin, Hui-Fan
DOI
zh-TW
Abstract
In the experiment, we use E-beam lithography to fabricate one-dimensional grating with deep nanostructure in order to enhance Raman scattering. This is a precursor research, and it is believed that the innovation of application and great result will benefit the following research.
The process to make the grating is first pattern-designing and exposure by E-beam lithography, and second etching by ICP-RIE. There are two experiments in the thesis. The first experiment is to measure the enhanced Raman scattering of silicon TO mode from silicon grating, and the second one is to measure the enhanced Raman scattering of rare concentration solution with grating deposited by silver thin film.
In this thesis, we modulate the line width and the period of grating. It can be verified by our experiment that both of the parameters has effects on the intensity of enhanced Raman scattering. I separate the results into two sections. In the first section, we fabricate silicon grating to enhance Raman scattering of silicon TO mode, and we supply TE and TM mode incident light sources for measurement. We don’t generalize the linear relationship between the line width and the stimulated Raman scattering, but at TM mode the influences from the line width is greater than that at TE mode. It can be thought that the incident light into grating will scatter the transverse wave so that the wave will stimulate the Raman scattering of silicon TO mode from the wall of grating and moreover the effect of wave at TM mode is stronger than that at TE mode. By modulating the period of grating, we can observe some different results from TM mode and TE mode. Whether at TM or TE mode the Raman intensity has a peak value (P ), nevertheless the change of intensity at TM mode has strong degree than that at TE mode. For wider period, the influences from TM and TE mode are approximate. But decreasing the period of grating to P , we can observe that the intensity from TM mode grows up faster. However, when the period is narrower than the P , the signal from TM mode is smaller than that at TE mode.
The second section is the results and discussion of enhanced Raman scattering of rare concentration solution with grating deposited by silver thin film. The great result is that we get the Raman scattering of molecule solution of which the concentration is rarer by 10 than that can be measured by the traditional Raman detection. Of all the samples with line width 120 nm and 150 nm can measure the lowest concentration which is about 10 to 10 g / c.c., however the samples with the wider or narrower line width will not measure the signal of such low concentration. With modulating the period, we observe that the in intensity is not linear relevant to the periods.
To enhance the Raman scattering with grating is a forerunner research, and consequently there are lots of research are going to be done. The great result inspires us to continue. In the future, we hope to understand the mechanics, and to integrate the semiconductor process to fabricate the integrated optical detection devices.
Subjects
光柵
拉曼
奈米
電子束
光學檢測
腺嘌呤
稀薄濃度溶液檢測
grating
Raman
e-beam
optical detection
adenine
nanotechnology
TM
TE
Type
thesis
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