The effect of a thin protective ScN coating on the superconducting and structural properties of ultrathin NbN films

The influence of a thin scandium nitride (ScN) protective layer on the superconducting properties of niobium nitride (NbN) thin films deposited by reactive magnetron sputtering was investigated. A comprehensive analysis of the morphological, microstructural, and electrophysical properties of the thin films subjected to high-temperature annealing in an oxygen atmosphere is presented. The dependence of the critical transition temperature of the NbN thin film on the annealing temperature in an oxygen environment, both with and without the ScN coating, was established. X-ray reflectometry studies revealed that the ScN film serves as a protective layer even at annealing temperatures around 450$^\circ$C, without affecting the density and thickness of the NbN layer. It was demonstrated that the NbN thin film coated with an ScN layer is more resistant to aggressive environments than the uncoated NbN film.