Plasmonic properties of gold nanoparticles on silicon substrates: Understanding Fano-like spectra observed in reflection

Léo Bossard-Giannesini 1 Hervé Cruguel 1 Emmanuelle Lacaze 1 Olivier Pluchery 1, *
* Corresponding author
1 INSP-E6 - Physico-chimie et dynamique des surfaces
INSP - Institut des Nanosciences de Paris
Abstract : Gold nanoparticles (AuNPs) are known for their localized surface plasmon resonance (LSPR) that can be measured with UV-visible spectroscopy. AuNPs are often deposited on silicon substrates for various applications, and the LSPR is measured in reflection. In this case, optical spectra are measured by surface differential reflectance spectroscopy (SDRS) and the absorbance exhibits a negative peak. This article studies both experimentally and theoretically on the single layers of 16 nm diameter spherical gold nanoparticles (AuNPs) grafted on silicon. The morphology and surface density of AuNPs were investigated by atomic force microscopy (AFM). The plasmon response in transmission on the glass substrate and in reflection on the silicon substrate is described by an analytical model based on the Fresnel equations and the Maxwell-Garnett effective medium theory (FMG). The FMG model shows a strong dependence to the incidence angle of the light. At low incident angles, the peak appears negatively with a shallow intensity, and at angles above 30°, the usual positive shape of the plasmon is retrieved. The relevance of the FMG model is compared to the Mie theory within the dipolar approximation. We conclude that no Fano effect is responsible for this derivative shape. An easy-to-use formula is derived that agrees with our experimental data.
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Journal articles
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https://hal.archives-ouvertes.fr/hal-01401824
Contributor : Emmanuelle Lacaze <>
Submitted on : Wednesday, November 23, 2016 - 6:12:17 PM
Last modification on : Friday, May 24, 2019 - 5:24:13 PM

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Léo Bossard-Giannesini, Hervé Cruguel, Emmanuelle Lacaze, Olivier Pluchery. Plasmonic properties of gold nanoparticles on silicon substrates: Understanding Fano-like spectra observed in reflection. Applied Physics Letters, American Institute of Physics, 2016, 109 (11), pp.111901. ⟨10.1063/1.4962731⟩. ⟨hal-01401824⟩

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