Study of Gold, Silver and Copper Thin Films for Plasmonic Sensors Applications

The sensitivity response of plasmonic sensors depends, among other factors, on the thickness and metal used in the metallic thin film. In these films, the phenomenon of surface plasmon resonance occurs at the interface between the metal and the dielectric surrounding material. In this work we studied and compared the suitability for sensor application of gold, silver and copper films with different thicknesses. We started with the thermal deposition of the different thin films, then we performed UV-visible spectroscopy on these films to obtain their transmittance curves. From these curves and using a data analysis program, we fitted the transmittance with a Drude-Lorentz model which gives the thicknesses and permittivities of the metallic thin films. We tested the validity of the fitting by comparing the modeled permittivities with the literature. In addition, the reflectivity response of each film was measured and compared with simulated values. Finally, the best thin film was exposed to alcohol gas at different concentrations to evaluate its sensor properties.