Characterization of nickel silicides using EELS-based methods.

The characterization of Ni-silicides using electron energy loss spectroscopy (EELS) based methods is discussed. A series of Ni-silicide phases is examined: Ni₃Si, Ni₃₁Si₁₂, Ni₂Si, NiSi and NiSi₂. The composition of these phases is determined by quantitative core-loss EELS. A study of the low loss part of the EELS spectrum shows that both the energy and the shape of the plasmon peak are characteristic for each phase. Examination of the Ni-L edge energy loss near edge structure (ELNES) shows that the ratio and the sum of the L₂ and L₃ white line intensities are also characteristic for each phase. The sum of the white line intensities is used to determine the trend in electron occupation of the 3d states of the phases. The dependence of the plasmon energy on the electron occupation of the 3d states is demonstrated.