Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut , 5232 Villigen-PSI, Switzerland.
ACS Nano. 2014 Apr 22;8(4):3700-6. doi: 10.1021/nn500375z. Epub 2014 Mar 13.
Double-layer plasmonic nanostructures are fabricated by depositing metal at normal incidence onto various resist masks, forming an antenna layer on top of the resist post and a hole layer on the substrate. Antenna plasmon resonances are found to couple to the hole layer, inducing image charges which enhance the near-field for small layer spacings. For continued evaporation above the resist height, a sub-10 nm gap channel develops due to a self-aligned process and a minimal undercut of the resist sidewall. For such double layers with nanogap channels, the average surface-enhanced Raman scattering intensity is improved by a factor in excess of 60 in comparison to a single-layer antenna with the same dimensions. The proposed design principle is compatible with low-cost fabrication, straightforward to implement, and applicable over large areas. Moreover, it can be applied for any particular antenna shape to improve the signals in surface-enhanced spectroscopy applications.
双层等离子体纳米结构是通过在各种抗蚀剂掩模上以正常入射的方式沉积金属而制成的，在抗蚀剂柱的顶部形成天线层，在基底上形成孔层。发现天线等离子体共振与孔层耦合，诱导图像电荷，从而增强了小层间距的近场。对于在抗蚀剂高度之上的持续蒸发，由于自对准过程和抗蚀剂侧壁的最小下切，会形成小于 10nm 的间隙通道。对于具有纳米间隙通道的这种双层结构，与具有相同尺寸的单层天线相比，平均表面增强拉曼散射强度提高了 60 倍以上。所提出的设计原理与低成本制造兼容，易于实现，并且适用于大面积。此外，它可以应用于任何特定的天线形状，以提高表面增强光谱应用中的信号。
