OPTICAL-PROPERTIES OF BURIED COBALT DISILICIDE LAYERS IN SILICON

The optical reflectivity from highly conducting buried and exposed CoS i2 layers produced by Co ion implantation of Si substrates has been me asured over the energy range 0.012-6.2 eV (0.2-100 mum). Both as-impla nted and high temperature annealed heteroepitaxial layers were investi gated. The frequency dependant optical constants associated with the C oSi2 films were derived from the multicomponent reflectivity spectra; the analysis accounted for the contributions from the Si-CoSi2 interfa ces. A Drude term was used to describe the free carriers, and a classi cal oscillator model was included to simulate interband electronic tra nsitions for the CoSi2. The plasma frequency and relaxation time of th e free carriers were measured as a function of anneal conditions. A di rect correlation between the effective carrier concentration and the m easured channeling data from Rutherford backscattering was observed.