Since 2008, we propose to use LE-IBS as a versatile approach for wafer-scale fabrication of plasmonic nanostructures. Planar arrays of metallic nanoparticles (AgNPs) are embedded in a dielectric layer at a controlled nanometric distance beneath the free surface of an antireflective heterostructure. Engineering the architecture of the stacking layers has been demonstrated as a key to take simultaneously advantage of spectrally and spatially Localised Surface Plasmon Resonance (LSPR) but also of optical amplification. This has been proposed for enhanced spectroscopy and imaging.
The ability of these substrates for exalting optical signals has been recently tested on 2D layers (graphene and MoSe2 sheets) deposited on the dielectric surface. For this purpose nanostructured substrates have been elaborated by implanting Ag+ ions through a micrometric grid thereby the sheet is located on top of both a AgNPs area and a reference region without nanoparticles. The cartography of the Raman signal of the graphene layer shows a strong increase of the Raman signature in the regions where graphene is on top of the AgNPs (see figure below). The same experiment has been performed by replacing graphene by MoSe2. We again observe an increase of the Raman signature of MoSe2 in the region where the sheet is on top of the AgNPs. This exaltation is higher for the out-of-plane vibration mode demonstrating an easier coupling with the atoms vibrating in direction of the NPs. The fabrication of the same AgNPs into TiO2 layers allows enhancing carrier generation in the matrix by a synergistic effect between plasmon resonance in Ag nanoparticles and optical interferences
- (a) Scheme of the nanostructured substrate with the dielectric layer (SiO2) implanted with Ag+ through a grid defining implanted (with AgNPs) and unimplanted (without AgNPs) regions ; (b) optical image of the grid ; (c) optical image of the graphene sheet deposited on top of the substrate ; (d) Raman cartography of the 2D signature of graphene, showing an exaltation of the Raman signal in the region where the graphene is on top of the AgNPs.
- © CEMES-CNRS
Contact : robert.carles chez cemes.fr
 Three Dimensional Design of Silver Nanoparticle Assemblies Embedded in Dielectrics for Raman Spectroscopy Enhancement and Dark-Field Imaging, R. Carles, C. Farcau, C. Bonafos, G. Benassayag, M. Bayle, P. Benzo, J. Groenen, and A. Zwick, ACS Nano, 5, 8774–8782 (2011).
 Enhancing carrier generation in TiO2 by a synergistic effect between plasmon resonance in Ag nanoparticles and optical interférence, G. Cacciato, et al., Nanoscale 7, 32, 13468-13476 (2015).