Preparation of Fe-N Films by Sputtering with He Gas

Fe-N films were deposited on glass substrates by rf sputtering with a mixture of Ar, He and N2 gases. The relationship between the properties of the films and the plasma species was investigated by optical emission spectroscopy analysis. In the Ar+He+N2 plasma, many N2⁺ molecular ions were generated by He atoms in neutral excited metastable states through the Penning ionization, and contributed to the reaction of Fe with nitrogen. Fe-N films prepared with a very low N2 content of less than 0.03% exhibited a larger magnetization than ¿-Fe.