Influence of the interaction between metal particles on optical properties of Ag-Si3N4 composite films. I. Experiment

Ag-Si3N4 composite films with metal fractions of 20% and 33% were prepared by magnetron sputtering. The Ag particles inside the composite films were less than 5 nm in radius. The optical absorption and near-field enhancement properties of the composite films were measured. On the plots of optical absorption, the extra absorption was observed as well as the surface plasmon resonance absorption. The intensity of the extra absorption depended on the particle size and metal fraction. Moreover, the composite films with higher extra absorption had better near-field enhancement properties. These phenomena were possibly related with the interaction between Ag particles in composite films.