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 less than equivalent to 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 plus or minus 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.