Iron nitride thin films prepared by facing targets sputtering

Abstract

The iron nitride thin films have been deposited using a facing targets sputtering (FTS) system and a conventional dc diode magnetron sputtering system, and their crystallographic characteristics and magnetic properties have been investigated. The total gas pressure (PN₂+P_Ar) was set at 2 mTorr. The films deposited by the FTS system without heating the substrate at PN₂ below 0.3 mTorr possessed α‐Fe‐like structure with an increased lattice constant. At PN₂ of around 0.5 mTorr, a two‐phase mixture of α‐Fe and Fe_2–3N was formed in the films prepared in the FTS system, while ζ‐Fe₂N phase was formed in the films prepared by dc magnetron sputtering. The films prepared by FTS at PN₂ of 0.1 mTorr possessed α‐Fe and γ’‐Fe₄N structures when a substrate temperature (T_s) was in the range from 80 to 300 °C. The films deposited at T_s of about 150 °C possessed a saturation magnetization (M_s) of about 1700 emu/cm³, which is larger than that of pure iron films and coercivity (H_c) of about 1.5 Oe.