The optical properties of Ag-Si nano-composite films prepared by sputtering

Ag-Si nano-composite films were prepared with a co-sputtering technique and step-sputtering method, respectively. The step-sputtered sandwich Ag-Si sa mples with Ag islands of area fraction approximately 0.43 showed strong res onance absorption near 610 nm. In contrast, the resonance absorption was wi dened and weakened in the co-sputtered Ag-Si films with the Ag volume fract ion at approximately 0.26. The effective dielectric function of the composi te materials consisting of multi-stage nanosized metal particles (or cluste rs) was deduced based on the theory of Sheng. The calculated absorptive coe fficients from this modified model coincides very well with the measured sp ectra of co-sputtered Ag-Si composite films. (C) 2000 Elsevier Science B.V. All rights reserved.