Sputter deposition and XPS analysis of nickel silicide thin films

Binary component Ni-Si films of different compositions are fabricated on AISI 304L stainless steels by means of ion-beam sputter (IBS) deposition. The compositions of the thin films and the chemical states of elements are analysed by means of X-ray photoelectron spectroscopy (XPS). The phase formation is studied and discussed in view of Pretorius' effective heat of formation (EHF) model. The proportions of the resulting phases can then be deduced. The electronic structure for the various compositions is also qualitatively investigated from the XPS valence band spectra, suggesting the bonding changes from predominating metallic to covalent bonding in Ni-Si systems when Si content increases.