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TitleNanoplasmonic response of porous Au-TiO2 thin films prepared by oblique angle deposition
Author(s)Rodrigues, Marco S.
Borges, Joel Nuno Pinto
Proença, Maria Manuela Carvalho
Pedrosa, Paulo Eduardo Teixeira Baptista
Martin, Nicolas
Romanyuk, Konstantin
Kholkin, Andrei L.
Vaz, F.
KeywordsNanostructured materials
Gold nanoparticles
Thin films
Magnetron sputtering
Localized surface plasmon resonance
Oblique angle deposition (OAD)
thin films, magnetron sputtering
Issue date31-May-2019
PublisherIOP Publishing
Abstract(s)In this work, a versatile method is proposed to increase the sensitivity of optical sensors based on the localized surface plasmon resonance (LSPR) phenomenon. It combines a physical deposition method with the oblique angle deposition technique, allowing the preparation of plasmonic thin films with tailored porosity. Thin films of Au-TiO2 were deposited by reactive magnetron sputtering in a 3D nanostructure (zigzag growth), at different incidence angles (0° ≤ α ≤ 80°), followed by in-air thermal annealing at 400 °C to induce the growth of the Au nanoparticles. The roughness and surface porosity suffered a gradual increment by increasing the incidence angle. The resulting porous zigzag nanostructures that were obtained also decreased the principal refractive indexes (RIs) of the matrix and favoured the diffusion of Au through grain boundaries, originating broader nanoparticle size distributions. The transmittance minimum of the LSPR band appeared at around 600 nm, leading to a red-shift to about 626 nm for the highest incidence angle α = 80°, due to the presence of larger (scattering) nanoparticles. It is demonstrated that zigzag nanostructures can enhance adsorption sites for LSPR sensing by tailoring the porosity of the thin films. Atmosphere controlled transmittance-LSPR measurements showed that the RI sensitivity of the films is improved for higher incidence angles.
Publisher version
AccessRestricted access (UMinho)
Appears in Collections:CDF - GRF - Artigos/Papers (with refereeing)

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