2015-08-012024-05-15https://scholars.lib.ntu.edu.tw/handle/123456789/665781摘要：近年來，利用貴金屬顆粒產生表面增強拉曼散射(SERS)對單一分子進行偵測之技術在分子檢測及鑑定的應用上受到矚目。懸架式週期性之金領結型奈米結構已在我們過去的研究中發現可產生相當大的電場以應用於單分子檢測，並且以石墨烯作為檢測材料或基材在表面增強拉曼散射的應用也已經在近年的研究中被發現。本研究計畫目的為利用懸架式結構之優點，結合石墨烯此種新興材料作為懸架式基材，以使用於表面增強拉曼散射的應用。為了達成目的，溶膠凝膠法、電子束微影、以及島狀微影等技術將被應用於進行懸架式結構的製作。位於懸架式基材之上的金屬奈米結構將以兩種排列方式存在，分別為隨機分布以及週期性陣列。隨機分布之金屬奈米結構可利用化學合成方法進行製作，週期性排列之奈米結構陣列則利用電子束微影技術進行製程。外加電壓亦可應用來調控石墨烯之能隙，並且能在不改變其貴金屬材料結構下，延伸應用於各種光學檢測。 為了驗證本研究計畫之可行性，本研究團隊進行了以下的預先測試。首先，利用有限元素分析法對懸架式石墨烯基材進行力學分析，並證實石墨烯的強度足以支撐其上之金屬奈米結構。第二，利用有限差分時域法(FDTD)證實，在石墨烯懸架式基材上之金屬奈米結構與直接位於矽基材上之金屬奈米結構相比，其電磁場增益效果較強。第三，本研究團隊已成功地利用島狀微影技術，以CsCl作為遮罩層製作出奈米柱狀結構，並利用拉曼光譜測量證實其表面增強拉曼散射的效果。本研究將利用有限差分時域法尋找最佳條件的奈米結構用於表面增強拉曼散射，並實際製作並量測其光學性質。本計畫期許在實驗工作中將可對研究生在奈米製程以及光學領域的技術給予完整良好的訓練，而模擬結果將成為實際製程參數的參考依據，以期得到最大電漿共振的奈米結構。本研究製成之金屬奈米結構將不只能使用在單分子光譜上，在各種先進的光學特性、製程控制以及光資訊處理上也能被充分應用。 <br> Abstract: The discovery of single-molecule sensitivity via surface-enhanced Raman scattering (SERS) on resonantly excited noble metal nanoparticles has brought an increasing interest in its applications to the molecule detection and identification. Suspended periodic gold bowtie nanostructures have recently been shown in our study to give a large enhancement factor sufficient for single molecule detection. Applications of graphene on SERS as both a probed material and a substrate have been discovered recently. The purpose of this proposal is to utilize the advantage of the suspended structure and the newly discovered graphene as a substrate material to develop suspended graphene as a substrate for SERS applications. To achieve this, techniques of sol-gel method, electron beam lithography, and island lithography will be used to fabricate this suspended nanostructure. The metallic nanostructures of both random distribution and periodic arrays will be used for SERS applications. While the randomly distributed metallic nanoparticles can be achieved using the chemical synthesis method, the periodic metallic nanostructures can be obtained using electron beam lithography. The external voltage will also be applied to tune the band gap of graphene to extend its applications to various optical detections without changing the geometry of the metallic nanostructure. To examine the feasibility of our proposal, we have performed the following preliminary studies. First, finite element analysis was conducted to ensure that the suspended graphene is sufficiently strong to support the nanostructure. Second, finite-difference time-domain (FDTD) simulations were used to verify that the suspended graphene is better than graphene directly on a Si substrate in terms of the electromagnetic field enhancement. Third, we have successfully fabricated CsCl islands using island lithography and found a greater SERS signal of probed molecules for the nanopillar structure than the flat Au film. In the proposed work, we will use FDTD to find the optimum nanostructure for SERS. We will then process the nanostructure and perform the related optical measurements. Our experimental work would train the graduate students in the areas of nanofabrication and optical measurement techniques. Our simulation results would provide guidelines for the processing of the optimum nanostructure to maximize plasmon resonance. This would lead to the applications for not only single molecule spectroscopy but also a variety of advanced optical characterization, manipulation and optical information processing using metallic nanostructures.表面電漿子石墨烯模擬島狀微影技術電子束微影技術PlasmonicsGrapheneSimulationsIsland LithographyElectron beam lithography