Résumé
We demonstrate that including the second viscosity of an electron gas in the
hydrodynamic model allows for highly accurate modeling of the optical response
of heavily doped semiconductors. In our setup, which improves resonance
visibility compared to previous approaches, plasmon resonances become more
distinct, allowing for detailed analysis of the underlying physics. With
advanced fitting techniques based on a physics-informed cost function and a
tailored optimization algorithm, we obtain close agreement between simulations
and experimental data across different sample thicknesses. This enhanced
resonance visibility, combined with our integrated approach, shows that key
parameters such as doping level and effective electron mass can be retrieved
from a single optical measurement. The spatial dispersion taken into account in
the hydrodynamic framework is essential for accurately describing the optical
response of plasmonic materials in this frequency range and is likely to become
a standard modeling approach.