Influence of phosphorus content on the structure of nickel electroless deposits

Ni-P electroless films prepared from a sulfate-based solution using hypophosphite ion as a reducing agent were optically characterised by ellipsometry. The refractive indices were recorded as a function of the deposition time and the concentration of reductant in the plating bath. To complement the ellipsometric data, X-ray diffraction analysis was performed. It is shown that ellipsometric measurements can be used to elucidate the change from crystalline to amorphous-like phases induced by the phosphorus content and therefore to correlate the composition with the properties required for Ni-P technological applications.