title: Highly Reproducible and Sensitive SERS Substrates with Ag Inter-Nanoparticle Gaps of 5 nm Fabricated by Ultrathin Aluminum Mask Technique.
abstract: Applicable surface enhanced Raman scattering (SERS) active substrates require high enhancement factor (EF), excellent spatial reproducibility, and low-cost fabrication method on a large area. Although several SERS substrates with high EF and relative standard deviation (RSD) of signal less than 5% were reported, reliable fabrication for large area SERS substrates with both high sensitivity and high reproducibility via low-cost routes remains a challenge. Here, we report a facile and cost-effective fabrication process for large-scale SERS substrate with Ag inter-nanoparticle (NP) gaps of 5 nm based on ultrathin alumina mask (UTAM) surface pattern technique. Such closely packed Ag NP arrays with high density of electromagnetic field enhancement ("hot spots") on large area exhibit high SERS activity and excellent reproducibility, simultaneously. Rhodamine 6G molecules with concentration of 1 × 10(-7) M are used to determine the SERS performance, and an EF of ∼10(9) is obtained. It should be noted that we obtain RSDs about 2% from 10 random spots on an area of 1 cm(2), which implies the highly reproducible signals. Finite-difference time-domain simulations further suggest that the enhanced electric field originates from the narrow gap, which agrees well with the experimental results. The low value of RSD and the high EF of SERS signals indicate that the as-prepared substrate may be promising for highly sensitive and uniform SERS detection.
authors.affiliation: †Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P. R. China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Fu
authors.affiliation: ‡Institute for Physics and IMN MacroNano (ZIK), Technical University of Ilmenau, Prof. Schmidt Straße 26, 98693 Ilmenau, Germany.
authors.forename: Zhibing
authors.initials: Z
authors.lastname: Zhan
authors.affiliation: †Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P. R. China.
authors.forename: Jinxia
authors.initials: J
authors.lastname: Dou
authors.affiliation: †Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P. R. China.
authors.forename: Xianzheng
authors.initials: X
authors.lastname: Zheng
authors.affiliation: ‡Institute for Physics and IMN MacroNano (ZIK), Technical University of Ilmenau, Prof. Schmidt Straße 26, 98693 Ilmenau, Germany.
authors.forename: Rui
authors.initials: R
authors.lastname: Xu
authors.affiliation: †Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P. R. China.
authors.forename: Minghong
authors.initials: M
authors.lastname: Wu
authors.affiliation: †Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, P. R. China.|‡Institute for Physics and IMN MacroNano (ZIK), Technical University of Ilmenau, Prof. Schmidt Straße 26, 98693 Ilmenau, Germany.
authors.forename: Yong
authors.initials: Y
authors.lastname: Lei
keywords: Ag nanoparticles; SERS; high reproducibility; nanogaps of 5 nm; ultrathin alumina mask technique