Nanoplasmonic response of porous Au-TiO2 thin films prepared by oblique angle deposition
authors Rodrigues, MS; Borges, J; Proenca, M; Pedrosa, P; Martin, N; Romanyuk, K; Kholkin, AL; Vaz, F
nationality International
journal NANOTECHNOLOGY
author keywords nanostructured materials; gold nanoparticles; thin films; magnetron sputtering; localized surface plasmon resonance; oblique angle deposition (OAD); GLAD
keywords SURFACE-PLASMON RESONANCE; NANOSCALE OPTICAL BIOSENSOR; RANGE DISTANCE DEPENDENCE; METAL NANOPARTICLES; GOLD NANOPARTICLES; REFRACTIVE-INDEX; TIO2; SPECTROSCOPY; SHAPE; LSPR
abstract 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 degrees <= alpha <= 80 degrees), followed by in-air thermal annealing at 400 degrees 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 alpha = 80 degrees, 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 IOP PUBLISHING LTD
issn 0957-4484
year published 2019
volume 30
issue 22
digital object identifier (doi) 10.1088/1361-6528/ab068e
web of science category Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied
subject category Science & Technology - Other Topics; Materials Science; Physics
unique article identifier WOS:000461812600001
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journal impact factor 3.404
5 year journal impact factor 3.467
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