Ultralarge Area Sub-10-nm Plasmonic Nanogap Array by Block Copolymer Self-Assembly for Reliable High Sensitivity SERS.
ACS applied materials & interfaces(2018)
摘要
Effective surface enhancement of Raman scattering (SERS) requires strong near-field enhancement as well as effective light collection of plasmonic structures. To this end, plasmonic nanoparticle (NP) arrays with narrow gaps or sharp tips have been suggested as desirable structures. We present highly dense and uniform Au nanoscale gap array enabled by the customized design of NP shape and arrangement employing block copolymer self-assembly. Block copolymer self-assembly in thin film offers uniform hexagonal packed nanopost template arrays over the entire surface of 2 in. wafer. Conventional evaporative metal deposition over the nanotemplate surface allows precise geometric control and positional arrangement of metal NPs, constituting tunable, strong plasmonic near-field enhancement particularly at the "hot spots" near interparticular nanoscale gaps. Underlying field distribution has been investigated by a finite-difference time-domain simulation. In the detection of thiophenol, our Au nanogap array shows a remarkable enhancement of Raman intensity greater than ~104 a standard deviation as small as 12.3 % compared to planar Au thin film. In addition, Adenine biomolecules can be detected as low as a detection limit of 100 nM. Our approach proposes highly sensitive and reliable SERS based on a scalable, low-cost bottom-up strategy.
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关键词
nanogap,block copolymer,plasmonic,SERS,sensor
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