- Recovering effective thicknesses and optical properties of copper and copper oxide layers from absorbance measurements doi link

Auteur(s): Barchiesi Dominique, Cakir D., Grosges Thomas, Fréty Nicole, Anglaret E.

(Article) Publié: Optical Materials, vol. 91 p.138-146 (2019)

Ref HAL: hal-02077581_v1
DOI: 10.1016/j.optmat.2019.02.029
WoS: 000470938800021
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Nowadays, the recovering of both thicknesses and optical properties of nanometric multilayers is still a challenge. We propose a method to recover the effective relative permittivities and the thicknesses of copper/copper oxide layers, from absorbance spectra measured in the visible spectra. The experimental data are fitted with a model of classical light-matter interaction and a combination of two Drude-Lorentz laws to calculate the relative permittivities over the spectrum. The Particle Swarm Optimization and the evolutionary methods are used for the least-square fitting. A two steps study reveals that the relative permittivities of bulk cannot be used to fit adequately the absorbance curves. However, a perturbation of these reference values improves their fitting. The method is applied to the absorption spectra of a set of three copper samples that are progressively oxidized by six successive heat treatments.