Synthesis and magnetic properties of iron nitride films deposited on Ge(100) by reactive ion beam sputtering

Abstract

Iron nitride films were deposited on Ge(100) wafers by a reactive ion beam sputter deposition of iron in an ammonia atmosphere. The composition and microstructure of these films were monitored by Rutherford backscattering spectroscopy analyses and x-ray diffraction experiments. The magnetic properties of these films were determined by a vibrating sample magnetometer. It was found that Ge(100) substrate is profitable for epitaxial growth of the α′′ phase. The optimum ammonia pressure for α′/α′′ phase formation was about 5×10−4 Torr. The saturation magnetization σs of each as-deposited Fe–N film is higher than that of a pure iron film. However, the film with the highest α′/α′′ phase content did not exhibit the largest σs value. The variation of σs of the Fe–N films during annealing at a temperature of 180 °C in a flowing nitrogen atmosphere was also investigated. It was found that there is no direct relationship between the higher σs values and the α′/α′′ phase in these Fe–N films.