Optical properties of polycrystalline nickel silicides

Abstract

The near-normal reflectivity of polycrystalline ${\mathrm{Ni}}_3$Si, ${\mathrm{Ni}}_2$Si, NiSi, and ${\mathrm{NiSi}}_2$ from 0.01 to 6 eV and the dielectric functions obtained by Kramers-Kronig analysis are presented. The effect of an oxide overlayer on the optical properties is also considered. The low-energy response is discussed in terms of the Drude model and compared with the transport measurements. The higher-energy interband spectrum is interpreted on the basis of the calculated density of states and photoemission results. In particular, the optical structures of ${\mathrm{NiSi}}_2$ are correlated to interband transitions using the joint density of states obtained by band-structure calculations.