Multiple-scattering theories including correlation effects to obtain the effective dielectric constant of nonhomogeneous thin films

Existing theories for the effective optical properties of a ceramic-metal granular medium (cermet) are discussed within a multiple-scattering analysis and used as the starting point for including correlation effects. Analysis of the nucleation and growth process in cermets indicates that the correlation between the islands of the less abundant material are important in the study of optical properties. Multiple-scattering corrections are considered by solving the field equation in the first smoothing approximation. The results obtained with this model are compared with other theories and against experimental data of real cermets. Quantum-size-effect corrections to the dielectric constant of the metallic grains in dielectriclike cermets and their effect on the results of the theory are also analyzed. Finally, renormalization effects introduced through a T-matrix formalism are discussed. Comparison between the results of the proposed model and the experimental data for different cermets shows that the theory developed has better predictive value than earlier models and good agreement is obtained with experiment even when the metal concentration is large.