Dielectric confinement and surface plasmon damping in Au: semiconductor nanocomposite thin films

Au metal clusters are embedded in amorphous Si matrix using alternating sputtering method. Although the nominal thickness of Au metal layer was adjusted as small as 1 nm, the resultant microstructure showed the Bruggeman geometry consisting of a networked Au clusters. Using the thin film data of the constituent materials Au and Si, the optical absorption in the effective medium was calculated, and the effects of composite geometry, particle size, and shape distributions were analyzed. Inhomogeneous broadening of absorption band is thought to be most significant in this BG geometric sample, but the remaining discrepancy between the calculated and the measured absorption may be ascribed to the presence of energy dissipation process due to a finite Schottky barrier built up at the metal-semiconductor junction.