Single-Order, Subwavelength Resonant Nanograting as a Uniformly Hot Substrate for Surface-Enhanced Raman Spectroscopy

Abstract

The surface-enhanced Raman spectroscopy (SERS) activity and the optical reflectance of a subwavelength gold nanograting fabricated entirely using top down technologies on silicon wafers are presented. The grating consists of 120 nm gold cladding on top of parallel silica nanowires constituting the grating's lines, with gaps between nanowires <10 nm wide at their narrowest point. The grating produces inordinately intense SERS and shows very strong polarization dependence. Reflectance measurements for the optimized grating indicate that (when p-polarization is used and at least one of the incident electric field components lies across the grating lines) the reflectance drops to <1% at resonance, indicating that essentially all of the radiant energy falling on the surface is coupled into the grating. The SERS intensity and the reflectance at resonance anticorrelate predicatively, suggesting that reflectance measurements can provide a nondestructive, wafer-level test of SERS efficacy. The SERS performance of the gratings is very uniform and reproducible. Extensive measurements on samples cut from both the same wafer and from different wafers, produce a SERS intensity distribution function that is similar to that obtained for ordinary Raman measurements carried out at multiple locations on a polished (100) silicon wafer.

Double strain state in a single GaN/AlN nanowire: Probing the core-shell effect by ultraviolet resonant Raman scattering

“…19 Even if near-field Raman scattering (surface-enhanced and tip-enhanced Raman scattering) are still challenging techniques for semiconducting nanostructures studies, recent advances exploiting plasmonic effects are promising in view of the careful analysis of narrowest single NWs on specific substrates. 20,21 Here, we report on the UV μ-Raman spectroscopy of a single GaN/AlN NW grown by Molecular Beam Epitaxy (MBE). The bottom part of the GaN NW is covered by an AlN shell whereas the top part has a free lateral surface.…”

Near-Field Hot Spots in Gold Nanoplasmonic Templates and Their Use for Surface Enhanced Raman Scattering Sensing Application

“…Near-field localization and studies of SERS on a variety of plasmonic structures have been reported previously by various researchers [11][12][13][14][15]. It is also reported that twodimensional (2D) structures are superior compared to onedimensional (1D) structure.…”

“…Thus, engineering the plasmonic structures to achieve densely packed near-field spots or hot spots is a prior must. This optimized structure can be used to explore trace molecular detection, biological sensing, and molecular vibrational studies [1][2][3][4][5][6][7][8][9][10].…”

Fano resonance boosted cascaded optical field enhancement in a plasmonic nanoparticle-in-cavity nanoantenna array and its SERS application

“…The intercoupling between the bright mode and the dark mode occurs when the near field of one mode overlaps with and excites the near field of the other mode, which can be generated in certain coupled plasmonic nanostructures, such as the symmetry breaking nanocavity-NP system, 21 the nonconcentric ring-disk cavity, 23 the plasmonic nanoshell, 24 NP oligomer chains, 25 nanovoids, [26][27][28][29][30] nanostars, 31 and nanogratings. 32 The plasmonic Fano interference usually results in an asymmetric resonant peak dressing within a broad spectrum. 33 Complex plasmonic nanostructures, in which individual tiny metal NPs are coupled to certain extended metallic structures, are ideal systems for generating both CFE and mode hybridization, such as the plasmonic nanoparticle-in-cavity (PIC) nanoantenna array.…”