Spectroscopic ellipsometry modelling of thin AuSn films and nanostructures as plasmonics materials

Abstract

Abstract A considerable interest in nanostructured thin films from intermetallic compounds of noble metals (Ag and Au) and post-transition metals is raised due to their unique plasmonic properties, which makes them potential materials for application in photonics, catalysis and biosensing systems. In this work the possibility for deposition of polycrystalline AuSn thin films was investigated, as thin films with the same composition and different thicknesses (10-100 nm) were obtained by co-depositing of Au and Sn metals. The chemical composition was determined by X-ray microanalysis. The X-ray diffraction patterns indicated formation of the intermetallic compound AuSn in the thin films. The complex permittivity ε = ε′ - i.ε″ of the thin AuSn films as function of the thickness was investigated by spectroscopic ellipsometry. The possibility for application of nanostructures from the AuSn intermetallic compound as suitable substrates for the needs of surface-enhanced Raman and fluorescence spectroscopy in the spectral interval 2.8 - 4.7 eV was analysed.