Fabrication of Ag nanoparticle arrays on Polydimethylsiloxane(PDMS) and its application to Surface Enhanced Raman Scattering

• Main Author: 許凱傑
• Other Authors: Hai-Pang Chiang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/37388427118802550382

碩士 === 國立臺灣海洋大學 === 光電科學研究所 === 101 === In this thesis, we use nanosphere lithography (NSL) to produced surface-enhanced Raman scattering (SERS) substrate based on polydimethylsiloxane (PDMS) and study its SERS sensitivity. Polystyrene nanospheres with 1500nm, 1000nm, 820nm, 740nm in diameter were drop-coated on PDMS substrate. After deposition of silver film 120nm in thickness by using thermal evaporation, tape was employed to lift-off the nanospheres and R6G molecules were then adsorbed on the substrate to examine its surface-enhanced Raman scattering (SERS) performance. It is found that more pieces of fragments and cracks will be formed with smaller size of polystyrene nanospheres and we call this substrate as triangular fragment structure. Largest SERS enhancement factor of 6.5×〖10〗^6 could be achieved when using nanosphere 740nm in diameter and excited at the wavelength of 532nm. In addition, we compare SERS sensitivity of this new kind of SERS substrate with those of two kinds of SERS substrate our lab previously developed. One is triangular silver nanoparticle array made from nanosphere 430nm in diameter. Another is silver film over nanosphere (AgFON) with nanosphere 1000nm in diameter. By compared the SERS intensity of R6G molecules adsorbed on these substrate, triangular fragment structure has best performance. By using AutoCAD and COMSOL simulation software, we use 3D Finite Element Method to simulate the transmission, reflectance and electric field distribution of the substrate from scanning electron microscope (SEM) image of the structure. We found that strong electric field will happen in the gaps between the small cracks of the triangular fragment structure and gap modes between the cracks will possibly be the origins of SERS.