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

Dominique Barchiesi (1, 2) , Deniz Cakir (3) , Thomas Grosges (1, 2) , Nicole Fréty (4) , Eric Anglaret (3)

1 UTT - Université de Technologie de Troyes
2 Gamma3 - Automatic mesh generation and advanced methods
3 L2C - Laboratoire Charles Coulomb
4 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

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.

Mots clés: Optical properties of multilayers; Optical transmission coefficients; Optical properties of films; Inverse problems

Domaines: Physique Numérique [physics.comp-ph]; Physique mathématique [math-ph]

Dominique Barchiesi, Deniz Cakir, Thomas Grosges, Nicole Fréty, Eric Anglaret. Recovering effective thicknesses and optical properties of copper and copper oxide layers from absorbance measurements. Optical Materials, 2019, Optical Materials, 91, pp.138-146. ⟨10.1016/j.optmat.2019.02.029⟩. ⟨hal-02077581⟩