Optical characterisation of RF sputter coated palladium thin films for hydrogen sensing

Abstract

We investigate the optical properties of Pd thin films of the thickness 20-100nm deposited on Si wafer via RF sputter coating. The Pd samples are characterised using white light interfermometry for thickness and ellipsometry for refractive index. We demonstrate the independence of refractive index on film thickness above 20nm. Considerable discrepancy is found between our measurement and previously published complex refractive indices for both bulk and RF sputter coated Pd, indicating a high degree of dependence on deposition technique.