Fabrication of Plasmonic Nanostructures and Study on Its Optical Properties

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Project title

Code/計畫編號

NSC97-2112-M019-001-MY3

Translated Name/計畫中文名

電漿子奈米結構的製作與其光學性質之研究

Project Coordinator/計畫主持人

Hai-Pang Chiang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Optoelectronics and Materials Technology

Website

https://www.grb.gov.tw/search/planDetail?id=1996779

Year

2010

Start date/計畫起

01-08-2010

Expected Completion/計畫迄

31-07-2011

Bugetid/研究經費

1544千元

ResearchField/研究領域

光電工程

近幾年來對於電漿子的研究是一很有趣的課題，像是已知的小尺寸的金屬顆粒與入射波長的電場達到共振，可以增強電場，進而可以增強近場效應。這樣的金屬顆粒也能使用在表面增強拉曼散射的領域上，因為金屬顆粒會有增強電場的效果，所以也可以增強低濃度分子的拉曼訊號。近幾年來因為製程技術的開發，很多學者開始製作非球狀的金屬島，可以製作成金屬棒狀或是點狀等等，各式各樣的形狀，也可控制金屬島狀的大小、金屬島的高度、區域的分佈或是折射率的改變。隨著奈米材料製作技術的成熟，很多製造奈米金屬結構的技術是可以在一些設備上獲得,最好用的就是電子束微影術(E-beam Lithography，EBL)，它可以利用短波長且有高能量的電子(0.005nm的波長在50kv的加速下)去得到非常好的結果。EBL也可以加在最普便的掃描式電子顯微鏡(SEM)系統上面。在典型的E-beam使用上，會使用一道電子束掃描過一層由高分子組成的光阻表面。因為電子與光阻的交互作用會造成該區的化學鍵變化，會因為光阻材料的不同造成照光部分的鍵結容易或不容易溶解，這步驟稱為舉離，在舉離之後就可以很清楚的看到有週期性的奈米結構。當結合了光罩的蒸鍍接著舉離，在光阻的圖案就可以被轉換成很好控制維度跟距離的金屬奈米結構圖案。藉由可控制奈米島的形狀、大小、島嶼島之間的距離以及島的高度等等的一些參數，可增強表面增強拉曼散射(Surface Enhanced Raman Scattering ; SERS)效率。有研究報告指出，可以利用Goos-Hanchen (GH) 位移現象來製作感應器。在此之後又有研究報告指出，如果將一道光入射到金屬表面或是會吸光的介質中，其 Goos-Hanchen 位移不是一個正向位移而是一個負位移。近年來更是有許多的方式可以得到Goos-Hanchen 負位移現象，Goos-Hanchen 負位移現象在應用方面大部分是應用在感應器方面，最近研究報告更是利用Goos-Hanchen 負位移現象並結合表面電漿共振現象來製作生物感應器。基於過去幾年在表面電漿共振及奈米金屬顆粒的理論與實驗上的研究經驗與成果，我們計畫利用電子束微影術(E-beam Lithography，EBL)來製作金屬島陣列，藉由電子束微影術可準確的控制米金屬島的形狀、距離、大小及高度，以進行Goos-Hanchen 負位移量測、侷域表面電漿共振、奈米金屬薄膜的非線性光學性質以及增進奈米生物感測器靈敏度方面的研究。本計畫的第一年將著重於Goos-Hanchen 負位移量測，首先是先建立一套Goos-Hanchen 負位移量測系統以及建立起其現象之理論模擬，以便從理論與實驗有系統的研究Goos-Hanchen 負位移現象，並研究奈米金屬結構是否可以增強 Goos-Hanchen 負位移，計畫的第二年將利用電子束微影術(E-beam Lithography，EBL) 來製作金屬島陣列，接著利用此金屬島陣列加以研究表面增強拉曼散射(Surface Enhanced Raman Scattering ; SERS)效率，並利用Fullwave 模擬軟體進行有限差分時域法 (Finite Difference Time Domain, FDTD) 模擬研究此金屬島陣列的光學性質，計畫的第三年則將結合奈米金屬島陣列的製作技術與光相位量測系統以及Goos-Hanchen 負位移量測系統，研究如何進一步增進表面電漿共振生物感測器的靈敏度。Recently, plasmonics has become a very interesting research topic. It is well known that small-sized metallic particles can resonance with incident electromagnetic fields of specific wavelengths and strengthen the near field effect due to enhancement of electromagnetic fields. Such metallic particles can be applied to surface-enhanced Raman scattering (SERS). Metallic particles can enhance electromagnetic fields and they can therefore enhance the Raman signal of molecules with low concentration. Recently, because of the rapid development of lithography technology, many scholars start to fabricate non-spherical metal islands. They can fabricate all kinds of shape and size metallic dots, rods and so on. They can also control the shape, size, height, distribution region, and even refractive index change of metallic islands. Along with the progress of nano-material fabrication technology, many fabrication technologies of nano-material structures may be implemented by special equipments. Among these equipments, Electron Beam Lithography (EBL) is the most easy to operate. This technology can employ short wavelength and high energy electrons (0.005nm wavelength under 50kv acceleration) to obtain extremely good result. EBL also may be added in scanning electron microscope (SEM) system. In the typical EBL, electron-beam is employed to scan on the photoresistor surface which is composed of polymer. Because of the chemical bond change aroused from the interaction between electrons and the photoresistor in the explosion area, different photoresistor material can cause the irradiation area easy or not easy to dissolve. This process is called lift-off. Periodic nanostructures can be clearly resolved after lift-off process. When the processes of optical mask design and lift-off are properly integrated, metallic nanostructures with well-controlled dimension and distance can be converted from the patterns in photoresistor. By controlling the parameters in the metallic nanostructures, one can increase the enhanced factor of Surface Enhanced Raman Scattering. It is reported that sensor can be implemented by using Goos-Hanchen shift. And it is also reported that when light is incident to metal surface or absorption medium, the Goos-Hanchen shift will undergo negative shift instead of positive shift. There are many ways to achieve negative Goos-Hanchen shift and the major application of negative Goos-Hanchen shift is located in the field of sensors. Recently negative Goos-Hanchen shift combined with surface plasmon resonance (SPR) is reported to implement biosensors. Based on our research accomplishment at the topic of surface plasmon resonance and metallic nanoparticles in past few years, we propose to fabricate metallic islands arrays by using the electron beam lithography. By accurately controlling the shape, distance, size and height of metallic islands arrays, we can undergo the research of negative Goos-Hanchen shift, localized surface plasmon resonance (LSPR), nonlinear optical properties of metallic nano-islands arrays and further increasing the sensitivity of SPR sensor. In the first year of this project, we will focus on the measurement of negative Goos-Hanchen shift. First we will set up a negative Goos-Hanchen shift measurement system and theoretical simulation to study shift enhancement of negative Goos-Hanchen shift due to metallic nanostrucutres. In the second year of this project, we will fabricate the metallic islands arrays by using electron beam lithography, perform Surface Enhanced Raman Scattering on these metallic islands arrays and use Fullwave simulation software (Finite Difference Time Domain, FDTD) to study the optical properties of these arrays. In the third year of this project, we will combine fabrication technology of metallic islands arrays, negative Goos-Hanchen shift measurement system and surface plasmon resonance phase detection technique to study sensitivity enhancement of SPR sensor.

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Fabrication of Plasmonic Nanostructures and Study on Its Optical Properties

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