奈米球鏡微影術製作具奈米孔洞陣列之金屬薄膜應用於表面增強紅外光譜

在本論文中，我們將會運用奈米球鏡微影術製作C環（C-ring）狀的奈米洞陣列，接著蒸鍍金與二氧化鈦，經飄膜後置於名片洞（hole-mask）上成為free-standing的金屬薄膜。此結構的局域性表面電漿共振（LSPR）位於紅外光波段，藉由調整曝光與蒸鍍等參數，可應用於表面增強紅外光譜。　　我們使用直徑2 μm的polystyrene奈米球，藉由奈米球的自組裝排列特性，使其在已塗佈光阻的矽基板上形成單層緊密排列。接著以奈米球作為凸透鏡，將紫外光匯聚於光阻層，經顯影後得到特定形狀的奈米洞陣列。藉由改變曝光的傾角，並搭配旋轉載台，可製作出不同大小、粗細的C環奈米結構。然後我們進一步使用斜向蒸鍍製程，在光阻層鍍上一層足夠厚的金，便於接下來的飄膜，最後再正向鍍上一層二氧化鈦。在飄膜的步驟中，藉由丙酮將光阻舉離後，金膜會飄起。我們用名片洞將金膜撈出，使其平整的置於名片洞上，得到free-standing的金屬薄膜。　　我們接著用傅立葉轉換紅外線光譜儀（FTIR）測量金膜的光譜，觀察其局域性表面電漿共振發生的波段位置。此奈米結構主要有兩個共振模態，其中與X方向偏振電場共振之模態之一位於1500 – 1600 cm-1之間，涵蓋4-aminothiophenol (4-ATP) 之吸收光譜的三個特徵峰。我們將500 μM的4-ATP溶液滴在金膜上，加熱到60°C 加速溶劑的蒸發，待風乾後測量其穿透光譜。將此光譜扣除純金膜的穿透光譜，即可獲得在此範圍之訊號增強後的4-ATP吸收光譜。經由此技術，我們能以低成本製作出大面積具奈米洞陣列的金屬薄膜，且free-standing技術可減少基板對FTIR測量的影響。經由調整曝光及蒸鍍等參數，可以將此金屬薄膜用於多種不同分子的表面增強紅外光譜，加以應用於生物感測等領域。

關鍵字

奈米球鏡微影術；表面電漿共振；表面增強紅外光譜

並列摘要

In this study, we will demonstrate the fabrication of free-standing Au membranes with designed nano-hole arrays using Nanospherical-lens Lithography. The designated localized surface plasmon resonance (LSPR) of the designed nano-holes is in the spectral range of mid-infrared and is demonstrated to be the platform for surface-enhanced infrared absorption spectroscopy (SEIRA). The sample is prepared with polystyrene nanospheres with diameter of 2 μm, and then exposed by UV light at a tilt angle with sample rotation, fabricating photoresist holes shape like C-rings. After development, the sample is deposited with Au and TiO2, and lifted-off to form a free-standing membrane. Various parameters of the nano-hole arrays are studied, including the shape and sizes of nano-holes, and Au membrane thickness. Samples of different parameters are measured by FTIR, and their LSPR modes are analyzed. Theoretical modeling is also performed to determine the corresponding modes at different wavelengths. After optimizing these parameters, this Au membrane serves as the platform to detect 4-aminothiophenol (4-ATP) molecules by enhancing their absorption signals around 1490 and 1600 cm-1, which are correspondent to the vibrational modes of C=C bonds and NH2 scissoring respectively.

並列關鍵字

Nanospherical-Lens Lithography ； localized surface plasmon resonance ； surface-enhanced infrared absorption spectroscopy

參考文獻

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奈米球鏡微影術製作具奈米孔洞陣列之金屬薄膜應用於表面增強紅外光譜

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