Effects of microstructure on the optical properties of metal-semiconductor composites

Abstract Microstructural effects in metal-semiconductor heterogeneous composite media are discussed in terms of isolated and clustered metal particles in the semiconductor. The former give rise to sharp peaks in the absorption spectrum in these systems while the latter result in broad structureless absorption over a large wavelength range. The effects of relative amounts of these two structures in a composite on the absorption characteristics are examined in two systems, the S-l photocathode which consists of Ag particles suspended in a base layer of Cs 2 O and a surface layer in which the Ag is in vacuum and Ag particles dispersed in polycrystalline Si.