Permalloy stoichiometry by nuclear backscattering

The high mass-resolution capability of nuclear backscattering spectrometry with 4.7 MeV 4He ion beams has been used to study the stoichiometry of thin permalloy (NiFe) films. For film thicknesses <=250 A, the backscattering signals from isotopes of Ni and Fe are sufficiently resolved to allow accurate determination of stoichiometry; the Ni fraction can be determined to better than +-1%. Studies of the dependence of NiFe film stoichiometry on deposition method, film thickness and oxygen contamination indicate that NiFe stoichiometry is independent of film thickness and oxygen contamination, but electron-beam evaporation produces films slightly richer in Ni than does sputtering. (orig.)