Sensitive SERS detection at the single-particle level based on nanometer-separated mushroom-shaped plasmonic dimers
Sensitive SERS detection at the single-particle level based on nanometer-separated mushroom-shaped plasmonic dimers
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DOI：
10.1088/1361-6528/aaa691
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发表时间：
2018-01
期刊：
影响因子：
3.5
通讯作者：
Quan Xiang;Zhiqin Li;Mengjie Zheng;Qing Liu;Yiqin Chen;Lan Yang;Tian Jiang;H. Duan
中科院分区：
文献类型：
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作者：
Quan Xiang;Zhiqin Li;Mengjie Zheng;Qing Liu;Yiqin Chen;Lan Yang;Tian Jiang;H. Duan
具有纳米GaP(<；10 nm)的凸起金属纳米结构具有表面增强拉曼散射(SERS)的优势，它通过纳米GaP的协同效应和通过凸起的三维(3D)设计有效地与衬底解耦。在这项工作中，我们展示了一种无图案转移的过程，基于金属薄膜沉积过程中的间隙缩小效应，可以直接从3D抗蚀剂图案可靠地定义提升的纳米分离蘑菇形二聚体。通过控制抗蚀剂结构中纳米GaP的初始尺寸和随后沉积的薄膜厚度，金属纳米GaP可以在10 nm以下的尺度上以个位数的纳米精度进行调节。实验和模拟结果都表明，在蘑菇柱上的金二聚体比在圆柱形柱子或普通的SiO_2/Si衬底上的等离子体二聚体具有更高的SERS增强因子，这意味着纳米间隙升高的二聚体是实现各种等离子体应用的最大可能场增强的理想平台。
Elevated metallic nanostructures with nanogaps (<10 nm) possess advantages for surface enhanced Raman scattering (SERS) via the synergic effects of nanogaps and efficient decoupling from the substrate through an elevated three-dimensional (3D) design. In this work, we demonstrate a pattern-transfer-free process to reliably define elevated nanometer-separated mushroom-shaped dimers directly from 3D resist patterns based on the gap-narrowing effect during the metallic film deposition. By controlling the initial size of nanogaps in resist structures and the following deposited film thickness, metallic nanogaps could be tuned at the sub-10 nm scale with single-digit nanometer precision. Both experimental and simulated results revealed that gold dimer on mushroom-shaped pillars have the capability to achieve higher SERS enhancement factor comparing to those plasmonic dimers on cylindrical pillars or on a common SiO2/Si substrate, implying that the nanometer-gapped elevated dimer is an ideal platform to achieve the highest possible field enhancement for various plasmonic applications.