Tunable localized surface plasmon resonance by self-assembly of trimetallic and bimetallic alloy nanoparticles via Ag sublimation from Ag/Au/Pt tri-layers

In this work, various configurations, size, density and composition of AgAuPt and AuPt alloy NPs are demonstrated via the solid-state dewetting (SSD) of Ag/Au/Pt tri-layers on the transparent c-plane sapphire (0001) and the corresponding LSPR characteristics are thoroughly investigated along with the FDTD simulation. The SSD is adapted to convert the sputtered Ag/Au/Pt tri-layers into the definite alloy NPs based on the diffusion, inter-diffusion and energy minimization process. The resulting AgAuPt and AuPt NPs demonstrate much stronger plasmonic characteristics as compared to their counterparts with the tunable LSPR bands in the UV and VIS regions along with the various plasmon resonance modes such as dipolar (DR), quadrupolar (QR), multipolar (MR) and higher order (HO). Furthermore, the Ag atom sublimation demonstrates a significant role in the dewetting process, which significantly alters the size, shape and composition of alloy NPs, giving a rise to the development of AuPt NPs. In specific, the LSPR response attenuates with the sublimation, however, as the AuPt NPs in this study are significantly improved in terms of composition and configuration, i.e. shape, size and spacing, the LSPR responses are much stronger and dynamic as compared to the pure Pt NPs on sapphire in the previous studies.