Synthesis of tunable plasmonic metal-ceramic nanocomposite thin films by temporally modulated sputtered fluxes

Abstract

The scientific and technological interest for metal-dielectric nanocomposite thin films emanates from the excitation of localized surface plasmon resonances (LSPRs) on the metal component. The overall optical response of the nanocomposite is governed by the refractive index of the dielectric matrix and the properties of the metallic nanoparticles in terms of their bulk optical properties, size, and shape, and the inter-particle distance of separation. In order to tune the film morphology and optical properties, complex synthesis processes which include multiple steps-i. e., film deposition followed by post-deposition treatment by thermal or laser annealing-are commonly employed. In the present study, we demonstrate that the absorption resonances of Ag/AlOxNy nanocomposite films can be effectively tuned from green (similar to 2.4 eV) to violet (similar to 2.8 eV) using a single-step synthesis process that is based on modulating the arrival pattern of film forming species with sub-monolayer resolution, while keeping the amount of Ag in the films constant. Our data indicate that the optical response of the films is the result of LSPRs on isolated Ag nanoparticles that are seemingly shifted by dipolar interactions between neighboring particles. The synthesis strategy presented may be of relevance for enabling integration of plasmonic nanocomposite films on thermally sensitive substrates. Published by AIP Publishing.<p>Funding Agencies|LiU Research Fellows Program; LiU Career [Dnr-LiU-2015-01510]; Knut and Alice Wallenberg foundation [2015.0060]</p

Plasmonics of Diffused Silver Nanoparticles in Silver/Nitride Optical Thin Films

“…Herein, we report on the silver – hydrogenated aluminium nitride (AlN) 14,15 and silver – silicon nitride (SiN x ) systems in which we show significant silver diffusion and nanoparticle formation upon fabrication of the AlN/Ag/AlN and to SiN x /Ag/SiN x multilayers. We observe the intense localized surface plasmon resonance (LSPR) 16 peaks typically associated with metal-dielectric composites 17 and find that they can only be accounted for by Ag nanoparticle diffusion. Thus, the multilayer is effectively a hybrid metal-dielectric multilayer-composite structure and can potentially serve as the basis for a novel synthesis method for nanostructures 18 that exploit in-situ Ag diffusion and nanoparticle formation for applications such as optical switching 19,20 and memristor devices 21,22 , or applications that combine 23 SPR and LSPR such as ultra sensitive immunoassays 24 , DNA detection 25 , and enhanced surface plasmon-coupled emission 26 .…”

Preface to Special Topic: Reactive high power impulse magnetron sputtering

“…They suggest that this can be exploited in the manufacture of films with particular properties. Magnf€ alt et al 17 demonstrate a single-step synthesis process that allows for tuning the plasmonic response of Ag/AlO x N y nanocomposite thin films with high precision in the range from green ( 2.4 eV) to violet ( 2.8 eV). They achieve this by employing Modulated Impulse Magnetron Sputtering Interplay (MIMSI) which is essentially well-defined trains of electrical pulses applied to the cathode target, where each single pulse in a pulse train has a width of the order of a few tens of microseconds.…”