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Fe-O-N films were successfully deposited by magnetron sputtering of an iron target in Ar-N2-O2 reactive mixtures at high nitrogen partial pressure 1.11 Pa (Q(N2) = 8 sccm) using a constant flow rate of argon and an oxygen flow rate Q(O2) varying from 0 to 1.6 sccm. The chemical composition and the structural and microstructural nature of these films were characterized using Rutherford Backscattering Spectrometry, X-ray diffraction, and Conversion Electron Mössbauer Spectrometry, respectively. The results showed that the films deposited without oxygen are composed of a single phase of γ ″ -FeN, whereas the other films do not consist of pure oxides but oxidelike oxynitrides. With higher oxygen content, the films are well-crystallized in the α-Fe2O3 structure. At intermediate oxygen flow rate, the films are rather poorly crystallized and can be described as a mixture of oxide γ -Fe2O3/Fe3O4. In addition, the electrical behavior of the films evolved from a metallic one to a semiconductor one, which is in total agreement with other investigations. Comparatively to a previous study carried out at low nitrogen partial pressure (0.25 Pa), this behavior of films prepared at higher nitrogen partial pressure (1.11 Pa) could be caused by a catalytic effect of nitrogen on the crystallization of the hematite structure. [ABSTRACT FROM AUTHOR]

Tungsten oxide films are deposited onto glass and silicon substrates using reactive magnetron sputtering. Several studies have revealed difficulties in studying the electrical properties of resistive WOx films. The main objective of this work is to propose the capacitance meter as a method for studying the electrical properties of resistive WOx films. In addition, we aim to establish the correlation between the deposition process and WOx physico-chemical properties. The study of the W-Ar-O2 system hysteresis permitted us to gather the films into four zones, which were delimited by different oxygen flow rate intervals. The identification of these zones was confirmed by the deposition rate, target voltage, chemical composition and electrical properties of the films. A gradual evolution of the capacitance-voltage curves of the metal-oxide-semiconductor structures, with the WOx thin films as the oxide layer, was globally observed with increasing oxygen flow rate. Ion density (Nss) and flat band voltage (Vfb) evolved inversely to oxygen flow rate. The relationship between the evolution of Nss and Vfb and the increase in oxygen flow rate reflects the improvement in oxygen stoichiometry in the WOx films. The WOx-Si interface trap density distribution (Dit) was also studied using the Terman method. It was observed that the films closest to stoichiometry, i.e., WO2 or WO3, showed the lowest values of Dit and Nss. [ABSTRACT FROM AUTHOR]