Formation of iron nitride thin films with Al and Ti additives

Abstract

In this work, we investigate the process of iron nitride (Fe-N) phase formation using 2 at. % Al or 2 at. % Ti as additives. The samples were prepared with a magnetron sputtering technique using different amount of nitrogen during the deposition process. The nitrogen partial pressure (RN2) was varied between 0% and 50% (rest argon) and the targets of pure Fe, [Fe + Ti] and [Fe + Al] were sputtered. The addition of small amount of Ti or Al results in improved soft-magnetic properties when sputtered using RN2≤ 10%. It was found that the thermal stability of soft-magnetic phase increases considerably when Al or Ti additives were used. When RN2 is increased to 50% non-magnetic Fe-N phases are formed. We found that iron mononitride (FeN) phases (N at. % ∼50) are formed with Al or Ti addition at RN2 = 50% whereas in the absence of such addition ϵ-Fe3-xN phases (N at. % ∼30) are formed. It was found that the overall nitrogen content can be increased significantly with Al or Ti additions. On the basis of obtained result, we propose a mechanism describing formation of Fe-N phases with Al and Ti additives.