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 &agr;′′phase. The optimum ammonia pressure for &agr;′/&agr;′′phase formation was about5×10−4 Torr.The saturation magnetization&sgr;sof each as-deposited Fe–N film is higher than that of a pure iron film. However, the film with the highest &agr;′/&agr;′′phase content did not exhibit the largest&sgr;svalue. The variation of&sgr;sof 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&sgr;svalues and the &agr;′/&agr;′′phase in these Fe–N films. ©1997 American Institute of Physics.