Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
Small. 2014 Oct 15;10(19):3933-42. doi: 10.1002/smll.201400509. Epub 2014 Jul 3.
Fabricating perfect plasmonic nanostructures has been a major challenge in surface enhanced Raman scattering (SERS) research. Here, a double-layer stacked Au/Al2O3@Au nanosphere structures is designed on the silicon wafer to bring high density, high intensity "hot spots" effect. A simply reproducible high-throughput approach is shown to fabricate feasibly this plasmonic nanostructures by rapid thermal annealing (RTA) and atomic layer deposition process (ALD). The double-layer stacked Au nanospheres construct a three-dimensional plasmonic nanostructure with tunable nanospacing and high-density nanojunctions between adjacent Au nanospheres by ultrathin Al2O3 isolation layer, producing highly strong plasmonic coupling so that the electromagnetic near-field is greatly enhanced to obtain a highly uniform increase of SERS with an enhancement factor (EF) of over 10(7). Both heterogeneous nanosphere group (Au/Al2O@Ag) and pyramid-shaped arrays structure substrate can help to increase the SERS signals further, with a EF of nearly 10(9). These wafer-scale, high density homo/hetero-metal-nanosphere arrays with tunable nanojunction between adjacent shell-isolated nanospheres have significant implications for ultrasensitive Raman detection, molecular electronics, and nanophotonics.
制造完美的等离子体纳米结构一直是表面增强拉曼散射（SERS）研究中的一个主要挑战。在这里，在硅片上设计了双层堆叠的 Au/Al2O3@Au 纳米球结构，以带来高密度、高强度的“热点”效应。通过快速热退火（RTA）和原子层沉积工艺（ALD），展示了一种简单可重复的高通量方法来制造这种等离子体纳米结构。双层堆叠的 Au 纳米球通过超薄的 Al2O3 隔离层构建了具有可调纳米间距和高密度纳米结的三维等离子体纳米结构，产生了高度强烈的等离子体耦合，从而大大增强了电磁场近场，获得了高度均匀的 SERS 增强，增强因子（EF）超过 10（7）。异质纳米球组（Au/Al2O@Ag）和金字塔形阵列结构衬底都可以进一步提高 SERS 信号，增强因子（EF）接近 10（9）。这些具有可调相邻壳层隔离纳米球之间纳米结的晶圆级高密度同/异质金属纳米球阵列对于超灵敏拉曼检测、分子电子学和纳米光子学具有重要意义。
