Multidisciplinary Sensor Research Group , Electronics and Telecommunications Research Institute (ETRI) , Daejeon 34129 , Republic of Korea.
Department of Organic Materials and Fiber Engineering , Soongsil University , 369 Sangdo-ro , Dongjak-gu, Seoul 06978 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Dec 26;10(51):44660-44667. doi: 10.1021/acsami.8b17325. Epub 2018 Dec 11.
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 a 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 films offers uniform hexagonally packed nanopost template arrays over the entire surface of a 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 ∼10, a standard deviation as small as 12.3% compared to that of the planar Au thin film. In addition, adenine biomolecules can be detected with a detection limit as low as 100 nM. Our approach proposes highly sensitive and reliable SERS on the basis of a scalable, low-cost bottom-up strategy.
有效的表面增强拉曼散射（SERS）需要强近场增强以及等离子体结构的有效光收集。为此，具有窄间隙或尖锐尖端的等离子体纳米粒子（NP）阵列被认为是理想的结构。我们通过使用嵌段共聚物自组装来定制 NP 形状和排列，展示了一种高度密集和均匀的 Au 纳米级间隙阵列。嵌段共聚物在薄膜中的自组装提供了整个 2 英寸晶圆表面上均匀的六边形纳米柱模板阵列。在纳米模板表面上进行的常规蒸发金属沉积允许金属 NPs 的精确几何控制和位置排列，构成可调谐的强等离子体近场增强，特别是在颗粒间纳米级间隙附近的“热点”处。通过有限差分时域模拟研究了基础场分布。在对噻吩醇的检测中，我们的 Au 纳米间隙阵列显示出大于 ∼10 的拉曼强度显著增强，与平面 Au 薄膜相比，标准偏差仅为 12.3%。此外，腺嘌呤生物分子可以以低至 100 nM 的检测限检测到。我们的方法基于可扩展的、低成本的自下而上策略，提出了高度灵敏和可靠的 SERS。
