Study On The Fabrication And Performance Of Large-area Uniform And Sensitive SERS Substrates Based On SP Imaging Lithography

Surface-enhanced Raman scattering?SERS?,as an ultra-sensitive,simple,rapid,and nondestructive detection method,has been well applied in various applications.The enhanced Raman signals are mainly attributed to the electromagnetic?EM?enhancement,which originates from the excitation of surface plasmon resonance?SPR?on the surface of noble metallic nano-structures.The geometries and periodic arrangement of nano-structures greatly affect the excitation of SPR.Thus,to obtain the nano-structure substrates with higher SERS effect,the fabrication technology is very important.Recently,surface plasmon lithography?SPL?has emerged as a powerful tool for nano-patterning in academic and industrial research.As a new fabrication method,SPL is compatible with traditional optical devices and can break the optical diffraction limit.In this thesis,large-scale uniform and low-cost nano-particle array structures with different inter-nanoparticle gaps for SERS substrates are fabricated utilizing SP imaging lithography in SPL technique.The specific research contents are as follows:In this thesis,large-scale and uniform single-layer diamond Ag nano-particles?SD-Ag NPs?arrays with different inter-nanoparticle gaps for SERS substrates are fabricated utilizing SP imaging lithography technique and IBE technique.The detection on Rhodamine6G?R6G?with concentration of 10^-5M is performed in the SERS substrates with various gaps.Experimental results show that the enhancement factor?EF?larger than 10⁷ can be obtained at the inter-nanoparticle gap of 30 nm.It is notable that the relative standard deviations?RSDs?of the fabricated substrates are all less than 14%in an entire area of 100mm²,RSD less than 10%in a smaller area of 49?m²),indicating the fabricated SERS substrates are uniform.To understand the SERS enhancement mechanism,the EM field distributions of SD-Ag NPs arrays with different gaps are simulated by the CST method.Numerical results are in accord with experimental ones.2.In order to obtain lower cost SERS substrates with high sensitivity,high uniformity and high stability,we combine SP imaging lithography technology with vacuum thermal evaporation coating technology,to prepare large area?100 mm²?,sensitive,and uniform multi-layer diamond PR/Ag/Au nano-particles?MD-PR/Ag/Au NPs?on the reflective Ag layer for SERS substrates.R6G molecules with concentration of 10^-5M are used to determine the SERS performance of those structures,and the enhancement factor larger than 10⁷ is obtained,which is higher than that of the SD-Ag NPS array structure substrate.Besides,we obtain RSDs less than 15%from 21 random spots on an area of 100 mm²,which illustrates the highly reproducible signals.The SERS substrate fabricated by combining SP imaging lithography technology with vacuum thermal evaporation coating technology appear to be a straightforward approach for creating large-scale SERS substrates with low-cost,high-sensitivity for practical SERS applications.In particular,the MD-PR/Ag/Au NPs arrays also have high-stability,because Au can effectively protect Ag nano-particles against aerobic oxidation,thus improving the stability of SERS substrates.