Effects of Gases on the Properties of Vapor-Deposited Ni-Fe Films

Abstract

Effects of O₂, N₂, H₂, and H₂O on characteristics of vapor‐deposited Ni‐Fe films are determined with the aid of quadrupole and monopole gas analyzers. Data obtained for films deposited in getter‐ion or oil‐diffusion‐type vacuum systems show that the presence of high oxygen partial pressures during deposition has a pronounced effect on the anisotropy field, coercive force, magnetoelastic strain coefficient, and product of easy axis dispersion and anisotropy field, while the other gases tested have little if any effect on film properties. High oxygen pressures or slow deposition rates during formation of the initial few‐hundred‐angstrom layer, followed by ``normal'' deposition, showed that propagation of a physical structure established in the initial layer is probably not responsible for the effects brought about by oxygen. Post‐deposition annealing in an oxygen‐rich atmosphere resulted in changes of magnetoelastic strain coefficient, indicating a surface oxide effect and/or diffusion into the films. ``Soaking'' glass substrates in high oxygen partial pressures for a short time prior to deposition did not have a noticeable effect on film properties, but treatment of substrates with oxygen‐bearing chemicals prior to deposition did cause significant changes in film properties. Attempts to find oxides in the Ni‐Fe films by electron‐diffraction techniques were unsuccessful, but microscopy studies revealed smallest grain size in films which were deposited in the presence of highest oxygen pressures. Electron‐diffraction analysis of pure nickel and pure iron films deposited in oxygen‐rich atmospheres showed the presence of NiO, FeO, Fe₂O₃, and Fe₃O₄.