Self-organization and optical response of silver nanoparticles dispersed in a dielectric matrix

Abstract. Double ion-beam sputtering has been used to fabricate nanocermet multilayers consisting of silver nanoparticles sandwiched between Si 3 N 4 dielectric layers. The organization of the nanoparticles has been studied in detail by quantitative analysis of transmission electronic microscopy and atomic force microscopy images. Our results show that the nanoparticles deposited on a plane surface present an isotropic macroscopic in-plane organization while their vertical arrangement displays a topology-induced self-organization. The use of faceted alumina substrates with periodic hill-and-valley structures results in the formation of linear chains of silver particles along the valleys. In that case, transmission optical measurements reveal in-plane anisotropy

Self-organized growth and optical properties of silver nanoparticle chains and stripes

Self-organized chains and stripes of silver nanoparticles have been elaborated by ion-beam sputtering shadow deposition onto faceted alumina substrates. We show that the in-plane organization of the silver nanostructures can be controlled through the grazing-incidence conditions (angle and orientation of the atomic beam with respect to the nanostructured surface). Their optical properties are dominated by a surface-plasmon resonance whose spectral position depends on the polarization of the incident light (parallel or perpendicular to the facets of the alumina template) and that can be attributed to a strong electromagnetic coupling between individual nanoparticles

Waveguiding and correlated roughness effects in layered nanocomposite thin films studied by grazing-incidence small-angle x-ray scattering

International audienceLong-range interface correlations in C/Au/C and Ag/Si3N4 layered films consisting of metal nanoparticles embedded in amorphous matrices are investigated by atomic force microscopy, high-angle annular dark-field scanning transmission electron microscopy, x-ray reflectivity, and grazing-incidence small-angle x-ray scattering (GISAXS). We demonstrate that the GISAXS intensity of such systems is modulated by waveguiding and correlated roughness effects, which involve the use of a dynamical scattering theory to analyze the experimental data and to distinguish between both effects. Direct imaging methods and GISAXS experiments combined with quantitative analysis within the distorted wave-Born approximation thus provide complementary information. While no roughness correlation is observed in the C/Au/C trilayers, the surface roughness of the Si3N4 capping layers in the Ag/Si3N4 bilayers replicate the topography of the Ag nanoparticles resulting in a partial correlation, which decreases as the Si3N4 thickness increases

Gold and silver nanoparticles embedded in dielectric-capping layers studied by HAADF-STEM

The morphology and optical response of Au and Ag nanoparticles capped with dielectric amorphous Si3N4, BN, and Al2O3 layers are studied. Quantitative analysis of high-angle annular dark-field images obtained in a scanning transmission electron microscope and simulations of optical transmittance spectra are used to investigate the dependence of the morphology of the nanoparticles on the particle size and on the capping material. It is demonstrated that capping-layer effects induce a size-dependent and cap-dependent reshaping of the nanoparticles