The structure of amorphous Si–Ni alloys

EXAFS data has been obtained from both absorption edges for a series of amorphous Si-Ni alloys prepared by RE sputtering in thin film form over the whole composition range. All samples show a degree of chemical order, which apparently increases with increasing nickel content, with largely invariant interatomic distances and Debye-Waller factors. Small Angle X-ray Scattering shows that the samples containing less than 50% nickel are phase-segregated on the 30A scale. The experimental data for the low-nickel samples is interpreted in terms of an amorphous NiSi phase distributed within an amorphous Si matrix. High-nickel samples are single phase, showing a high degree of chemical order.