Structure, electrical conductivity, critical superconducting temperature and mechanical properties of TiNxOy thin films

For thermal applications, one needs to manufacture titanium nitride based films with as high as possible critical superconductivity temperature while minimizing the mechanical constraints. We investigated the structural and mechanical properties of titanium oxynitride thin films TiNxOy with 0.385 ≤ x ([N] / [Ti]) ≤ 1.13 and y ([O] / [Ti]) ≤ 0.3 deposited in a temperature range of 320–400 K, at 800 W, by reactive DC magnetron sputtering deposition from a Ti target in Ar + N2 plasma discharge. The working pressure was fixed at 0.2–0.25 Pa and the nitrogen concentration, x, modified by increasing the N2 flow from 4.2 to 15 sccm. The Ar flow was set at 60 sccm. We thus tried different physical conditions during realization and characterized the films obtained. We also studied the influence of the substrate onto these film properties. The chemical analysis was performed with the Rutherford backscattering and nuclear reaction analysis techniques. The structural properties of the films were characterized by X-ray diffraction and the mass density by X-ray reflectivity. The electrical resistivity and the critical superconducting temperature were measured by the four-point probe method. Acoustic and elastic properties were determined by the picosecond ultrasonic and the Brillouin light scattering techniques as a function of the nitrogen concentration.