| Summary: | 碩士 === 國立臺北科技大學 === 高階管理碩士雙聯學位學程 === 106 === This thesis proposes two new lithium niobate ferroelectric templates to produce the SERS substrates. Both SERS substrates are designed and fabricated by using the periodically proton exchange process. The control of the diluted concentration of benzoic acid and the tip height of the proton exchange regions is utilized to produce the best photoreduced silver nanostructures for efficient enhancement of the Raman signal. In the experiments, the surface characteristics of lithium niobate ferroelectric template, and the distribution of silver nanostructures are measured by using the optical microscope, the scanning electron microscope (SEM), atomic force microscope (AFM), and electrostatic force microscope (EFM). This thesis also discusses the effect of fabrication parameters on the shape, the diameter, and particle density of the silver nanostructure.
The first kind of SERS substrates has a periodically diluted proton exchange structure. By using benzoic acid mixed with lithium benzoate, the concentration of proton exchange is changed such that the concentration of proton in lithium niobate can be controlled. This could produce the most suitable electrostatic field on the substrate surface to produce the photoreduced silver nanostructure which had the best enhancement of Raman signal intensity. Experimental results show that the Raman signal intensity can be enhanced by 8.63 times in comparison with the conventional samples. The relative standard deviation of Raman signal intensity at eight points on the substrate is under 10.4%.
The second kind of SERS substrates utilizes the tip effect on the rough substrate surface to assist the production of photoreduced silver nanostructures. In the fabrication process, the HF solution is used to etch proton exchange region. By the strong electrostatic field from the tips on the rough surface, the interaction of photocurrent and silver ions is promoted to form high-density sand the uniform silver nanoparticles. The experimental result shows that the Raman signal can be enhanced by 10.76 times and the relative standard deviation of Raman signal intensity at eight points on the substrate surface is under 9.7%.
In comparison with the conventional SERS substrates produced by periodically proton-exchanged process, these two kinds of the new SERS substrates using the optimal fabrication parameters in this thesis have the Raman signal intensity enhanced by over than 8.63 times. The relative standard deviation of Raman signal intensity at eight points on the substrate surface is under 10.4%, which is close to the standard value of 10%. These two novel SERS substrates produced by ferroelectric templates have the advantages of no need of using reducing agent, repeatable use of SERS substrate, and large-area fabrication. This study is helpful to the development of the future application of ferroelectric templates in the commercialized SERS substrates.
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