Centre d’Élaboration de Matériaux et d’Etudes Structurales (UPR 8011)


Accueil > Recherche > NeO : Nano-Optique et Nanomatériaux pour l’Optique > Nanoparticules dans les Diélectriques - Synthèse Ionique

Coupling of the Ag nanoparticles with graphene

Recently, we associated our embedded Ag nanostructures to few-layer graphene (FLG), the OD nanostructures and 2D layer being at controlled nanometer distance from each other in a same composite material. Our aim was to propose a new way to modify in specific areas the electronic and optical properties of graphene layers without any contact.

For this experiment, implantation of Ag+ ions has been performed through a two-dimensional copper grid mechanically plated on the surface of the SiO2 antireflective layer on top of a Si substrate using removable clips. Hence, 2D design of the grid is perfectly printed as a 2D plasmonic architecture embedded into the insulating silica layer.

We analysed vibrational and electronic Raman Scattering (ERS, i. e., the spectrum “background”) in the FLG deposited on SiO2/Si substrate, in which plasmonic AgNPs have been buried a few nanometers underneath the free surface, and have shown an intensity enhancement due to the electromagnetic mechanism. The intensity of the first order graphene G band is enhanced by the coupling with the AgNPs and particularly at the edge the sheet while the frequency of its maximum is rather unchanged (left figure). In addition, the frequency of the second order 2D band downshifts and its FWHM increases while its intensity is less enhanced than the G mode (right figure). The downshift of the 2D band position has been ascribed to n-doping of graphene. The strong ERS signal observed is additional evidence of a plasmon-assisted optical injection of electrons in the graphene layers.

Left : Raman spectra corresponding to the 5 characteristic zones as defined in the inset ; right : second order Raman bands of the trilayer graphene sheet : on SiO2/Si (green curve), in the vicinity of AgNPs (red curve) and at the edge between these two regions (purple curve). The inset corresponds to the integrated intensity of the 2D band.

Plasmon-enhanced scattering and charge transfer in few-layer graphene interacting with buried printed 2D-pattern of silver nanoparticles, Carles, R. ; Bayle, M. ; Bonafos, C., nanotechnology, 29, 175301 (2018).

Funding : This study has been funded by the LANCE NEXT project.