Optical Properties of Ultra-thin Metal Films

While the optical properties as well as the DC-conductivity of thicker metal films are well understood, little has been done at and below the metal-to-insulator transition (percolation threshold), especially in the infrared and far-infrared region. Here we present temperature dependent FTIR measurements on ultra-thin Au films on Si(111 ) in the thickness range between about one monolayer and 9 nm.