Structural, optical and electrical properties of reactively sputtered iron oxynitride films

In this paper, the properties of iron oxynitride films prepared by magnetron sputtering of an iron target in Ar–N2–O2 reactive mixtures using constant nitrogen and argon flow rates are presented. The oxygen flow rate varied from 0 to 2 sccm. The thickness of the films deposited on silicon substrates ranged from 0.2 to 2 µm. The structure and chemical composition of these films were determined by x-ray diffraction and Rutherford backscattering spectrometry, respectively. These studies revealed the formation of a new fcc intermediate phase of iron oxynitride FeNxOy films between iron nitride (ε-Fe2N) and an oxide close to Fe2O3. In addition, optical and electrical properties measurements at room temperature were investigated during this work. Refractive index and extinction coefficient were determined from spectroscopic ellipsometry. The electrical behaviour of the films evolved from a metallic one to a semiconductor one which is consistent with other investigations. In order to determine the morphology of the films, scanning electron microscopy was used.