Investigation of surface plasmon resonance in Au nanoparticles deposited on ZnO:Al thin films

Spectroscopic ellipsometry in external reflection (ER) and total internal reflection (TIR) modes is used to characterize surface plasmon resonance in Au nanoparticles (AuNPs) deposited on Al-doped ZnO films via surface thiolation. ER ellipsometry exhibits high sensitivity to the alkanethiol layer as well as to localized surface plasmons at energies around 2.3 eV. TIR ellipsometry reveals resonances at higher energies (2.9–3.35 eV), which are dependent on the environment used: air or deionized water. Coupling between charge dipoles inside the AZO layer and surface plasmons may account for the existence of those resonances.