Design of Hybrid Nanostructural Arrays to Manipulate SERS-Active Substrates by Nanosphere Lithography

Abstract

An easy-handling and low-cost method is utilized to controllably fabricate nanopattern arrays as the surface-enhanced Raman scattering (SERS) active substrates with high density of SERS-active areas (hot spots). A hybrid silver array of nanocaps and nanotriangles are prepared by combining magnetron sputtering and plasma etching. By adjusting the etching time of polystyrene (PS) colloid spheres array in silver nanobowls, the morphology of the arrays can be easily manipulated to control the formation and distribution of hot spots. The experimental results show that the hybrid nanostructural arrays have large enhancement factor, which is estimated to be seven times larger than that in the array of nanocaps and three times larger than that in the array of nanorings and nanoparticles. According to the results of finite-difference time-domain simulation, the excellent SERS performance of this array is ascribed to the high density of hot spots and enhanced electromagnetic field.

Ag Nanotwin-Assisted Grain Growth-Induced by Stress in SiO2/Ag/SiO2 Nanocap Arrays

“…As the temperature increased, the gap between the nanocaps gradually became larger, which led to weakened couplings between the neighboring nanocaps. When the samples were annealed at 400 °C, the surface of the nanocap became smooth; the Ag grain growth reduced the coupling between the particles in the nanocaps, which led to the decreased “hot spot” in each nanocap [ 39 , 40 ]. At 800 °C, the SERS intensity was the lowest, but the enhancement factor (EF) was about 10 7 .…”

Increasing local field by interfacial coupling in nanobowl arrays

“…The value of silver permittivity and permeability used in simulations were provided by the soware material database. 26…”

“…Noble metal Ag and dielectric SiO 2 are most popular complex materials for SERS substrate due to strong plasma characteristic of Ag and insulative property of SiO 2 . Recently, some nanostructures, like nanofollowers, 26 nanobowls, 27 nanoposts, 28 which consist of Ag and SiO 2 , have been fabricated as SERS substrate by the combination of NSL and physical deposition.…”

Large-Area and Patternable Nano-Dot Array from Electrolysis of ITO Film for Surface-Enhanced Raman Spectroscopy

“…The nanoparticle systems are easy-to-use, however lack of repeatability and reproducibility with relatively low sensitivity [5,6]. Nanostructures fabricated by e-beam lithography [7,8], laser interference lithography [9,10], focused ion beam lithography [11], nanosphere lithography [12], and nanoimprint lithography [13] have shown high signal enhancement with excellent repeatability. However, these nanofabrication technologies require expensive equipment and restrict environment like ultraclean room; and the fabrication process is slow, as well.…”