Controlling the 3D Electromagnetic Coupling in Co-Sputtered Ag–SiO2 Nanomace Arrays by Lateral Sizes

Abstract

Ag–SiO2 nanomace arrays were prepared on a two-dimensional ordered colloidal (2D) polystyrene sphere template by co-sputtering Ag and SiO2 in a magnetron sputtering system. The lateral size of the nanomaces and the distance between the neighbor nanomaces were controlled by adjusting the etching time of the 2D template. The nanomaces were composed of SiO2-isolated Ag nanoparticles, which produced surface-enhanced Raman scattering (SERS) enhancement, and 3D hot spots were created between the neighbor nanomaces. When the distance between the nanomaces was sufficiently large, triangle-shaped nanostructures on silicon substrate were observed, which also contributed to the enhancement of the SERS signals. The finite-difference time-domain (FDTD) method was used to calculate the electromagnetic field distributions in the Ag–SiO2 nanomace arrays, which generated physical reasons for the change of the SERS signals.

Manipulation and Applications of Hotspots in Nanostructured Surfaces and Thin Films

“…Various nanostructured surfaces and thin films can be achieved by the combination of NSL and physical vapor deposition, such as periodic nanocaps [ 14 , 15 , 16 , 17 , 18 ], nanotriangles [ 19 , 20 , 21 , 22 ], nanobowls [ 23 , 24 , 25 ], nanorings [ 26 , 27 , 28 ], nanopillars [ 29 , 30 ], nanocones [ 31 , 32 , 33 ], and other complex nanostructured surfaces and thin films, including nanohoneycomb, bridged knobby units, nanoparticle cluster-in-bowl arrays, and so on [ 2 , 25 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. These architectural designs of nanostructured surfaces and thin films can be obtained by controlling a series of deposition processes (the deposition time, angle, distance, and so on), PS colloid sphere etching, transfer, and their combination steps, which manipulate the formation, distribution, and evolution of hotspots and have significant implications in broad applications [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 …”