Silver-coated elevated bowtie nanoantenna arrays： Improving the near-field enhancement of gap cavities for highly active surface-enhanced Raman scattering

• Published in: Nano research 2015-11, Vol.8 (11), p.3715-3724
• Main Authors: Feng, Lei, Ma, Renping, Wang, Yandong, Xu, Daren, Xiao, Dongyang, Liu, Lingxiao, Lu, Nan
• Format: Article
• Language: English
• Subjects: Arrays; Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Cavities; Chemistry and Materials Science; Condensed Matter Physics; Devices; Finite difference method; Holes; Lithography; Materials Science; Nanoantennas; Nanospheres; Nanostructure; Nanotechnology; Raman scattering; Raman spectra; Reproducibility; Research Article; Silver; Substrates; 天线阵列; 纳米级; 结型; 表面增强拉曼散射; 近场; 镀银; 间隙; 高活性
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-015-0871-2

Improving hot-spot intensity is a key issue in surface-enhanced Raman scattering （SERS）. The bowtie nanoantenna （BNA） is an effective device used to concentrate light energy into a nanoscale volume and produce strong hot spots. Nanosphere lithography （NSL） is a large-area and low-cost technique to produce BNA arrays; however, the SERS activity of NSL-fabricated BNAs is limited. In this paper, we present a simple method to improve the SERS activity of conventional NSL-fabricated BNAs by modifying their geometry. The new configuration is termed ＂silver-coated elevated bowtie nanoantenna＂ （SCEBNA）. SCEBNAs perform intensive near-field enhancement in the gap cavities owing to the integrated contribution of the ＂lightning rod＂ effect, resonance coupling, and the formation of the plasmonic Fabry-Perot cavity. Experimental measurements and finite-difference time-domain simulations revealed that the hot-spot intensity and the substrate enhancement factor can be optimized by adjusting the silver thickness. The optimal sample has the capability of trace-amount detection with fine reproducibility.