Abstract
The formation of a transition metal-rich, glassy Si layer, followed by nucleation of a metallic suicide has been postulated to account for Schottky barrier behavior, and observed through transport and transmission electron-diffraction (TED) measurement. We report here the results of a multiple-angle-of-incidence ellipsometry study of the Co/Si interface for varying Co deposit thickness. As the Co deposit thickness is increased, initially a layer forms at the surface of the Si, which has the increased refractive index and extinction coefficient (at 6328 Å) characteristic of amorphous and ion-implanted Si. For deposit thicknesses larger than ~70 Å, the refractive index drops sharply to values below that for the bulk Si, while absorption continues to increase. This transition thickness agrees quantitatively with the value at which the semiconducting-to-metallic transition has been observed in transport measurements, and the optical constants obtained here are believed to be characteristic of that transition. © 1980.