Properties of ultrathin epitaxial NbNx film on C-cut sapphire

Here we report on the results of obtaining and study of epitaxial ultrathin superconductive films of niobium nitride grown on a C-plane sapphire substrate. The films were deposited from metal-organic precursor using the plasma-enhanced atomic layer deposition. We employed X-ray diffraction, and high-resolution transmission electron microscopy techniques to study the structural properties of the films. We also determined the quasiparticle diffusion constant, the coherence length, the superconducting transition temperature, the critical current density, and the non-uniformity of the resistance distribution of niobium nitride films.