在拉曼散射光譜中的散射強度相當微弱，若待測物的濃度相當低則會使此項分析具有相當大的挑戰性，因此表面增強拉曼散射 (Surface-Enhanced Raman Scattering, SERS) 這項提升拉曼訊號的技術近年來快速的發展，而在這項技術中製備乾淨及高SERS活性基板的再現性仍存在許多限制。在本研究中利用模板輔助沉積奈米銀粒子陣列於矽基板上以期作為SERS之應用，利用二次陽極氧化鋁 (Anodic Alumina Oxide, AAO)模板作為蒸鍍的遮罩用以成長奈米銀粒子陣列，在製程中可藉由調整模板的孔徑大小及蒸鍍之厚度，控制奈米銀粒子陣列的尺寸、形狀及間距。由研究結果得知，孔徑尺寸及粒子間距之比例 (Interspacing Ratio ,γ)將影響SERS活性，似半球形之Ag NP2具有較大的γ值 (8.82)使其在SERS性質的提升大於γ值較小之Ag NP1 (4.32)；而有趣的是，錐狀的奈米銀具有最高的SERS活性。無論是似半球型或錐狀的奈米銀粒子陣列皆可有效的提升拉曼訊號，與塊材的基板相比，在羅丹明6G (Rhodamine 6G)濃度為10-6M時可提升拉曼訊號約107倍。Due to the very small scattering intensity of ordinary Raman spectroscopy, the detection of analytes at very low concentration is a very challenging problem. It drives a rapid development of surface-enhanced Raman scattering (SERS) to amplify the Raman signals. However, it is still mainly limited by the reproducible preparation of clear and highly SERS-active substrate.In this study, we introduced template-assisted deposition method to fabricate silver nanoparticle arrays on Si wafer for SERS application. The free standing through holes anodic alumina oxide (AAO) templates were firstly prepared by two step anodization and used as masks during vapor-phase deposition. Tunable size, shape and spacing of silver nanoparticle arrays can be obtained by adjusting the pore size of templates and changing the deposited silver thickness. It was found that the diameter size and interspacing ratio (γ) affects their SERS activity, hemispherical-like Ag NP2 which has larger γ 8.82 performed higher enhancement properties than that of Ag NP1with γ 4.32. Interestingly, (cone-like Ag nanoparticles, Ag NC) which has sharp edge at the top showed the highest activity among others. These SERS-active substrates drastically enhanced the Raman signals of 10-6 M Rhodamine 6G up to 107 folds compared to the bulky reference.
