  Understanding the interaction between plasmonic nanoparticles and transparent
conductive oxides is instrumental to the development of next-generation
photovoltaic, opto-electronic and energy-efficient solid-state lighting
devices. We investigated the optical response of hybrid media composed of gold
nanoparticles deposited on aluminum-doped zinc oxide thin films with varying
doping concentration by spectroscopic ellipsometry. The dielectric functions of
bare AZO were addressed first, revealing doping-induced effects such as the
band-gap shift and the appearance of free carriers. In the hybrid media, a
blueshift of the localized surface plasmon resonance of Au NPs as a function of
increasing Al-doping of the substrate was observed, ascribed to the occurrence
of a charge transfer between the two materials and the doping-dependent
variation of the polarizability of the substrate.
