title: M-shaped grating by nanoimprinting: a replicable, large-area, highly active plasmonic surface-enhanced Raman scattering substrate with nanogaps.
abstract: Plasmonic nanostructures separated by nanogaps enable strong electromagnetic-field confinement on the nanoscale for enhancing light-matter interactions, which are in great demand in many applications such as surface-enhanced Raman scattering (SERS). A simple M-shaped nanograting with narrow V-shaped grooves is proposed. Both theoretical and experimental studies reveal that the electromagnetic field on the surface of the M grating can be pronouncedly enhanced over that of a grating without such grooves, due to field localization in the nanogaps formed by the narrow V grooves. A technique based on room-temperature nanoimprinting lithography and anisotropic reactive-ion etching is developed to fabricate this device, which is cost-effective, reliable, and suitable for fabricating large-area nanostructures. As a demonstration of the potential application of this device, the M grating is used as a SERS substrate for probing Rhodamine 6G molecules. Experimentally, an average SERS enhancement factor as high as 5×10⁸ has been achieved, which verifies the greatly enhanced light-matter interaction on the surface of the M grating over that of traditional SERS surfaces.
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China; Tsinghua-Foxconn Nanotechnology Research Center, Department of Physics, Tsinghua University, Beijing, 100084, China.
authors.forename: Zhendong
authors.initials: Z
authors.lastname: Zhu
authors.forename: Benfeng
authors.initials: B
authors.lastname: Bai
authors.forename: Huigao
authors.initials: H
authors.lastname: Duan
authors.forename: Haosu
authors.initials: H
authors.lastname: Zhang
authors.forename: Mingqian
authors.initials: M
authors.lastname: Zhang
authors.forename: Oubo
authors.initials: O
authors.lastname: You
authors.forename: Qunqing
authors.initials: Q
authors.lastname: Li
authors.forename: Qiaofeng
authors.initials: Q
authors.lastname: Tan
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Shoushan
authors.initials: S
authors.lastname: Fan
authors.forename: Guofan
authors.initials: G
authors.lastname: Jin
keywords: gratings; localized surface plasmons; nanoimprinting; near-field enhancement; surface-enhanced Raman scattering