Abstract

We study the crystalline structure and superconducting properties of gamma-Mo2N thin films grown by reactive DC sputtering on AIN buffered Si (001) substrates. The films were grown at room temperature. The microstructure of the films, which was studied by X-ray diffraction and transmission electron microscopy, shows a single-phase with nanometric grains textured along the (200) direction. The films exhibit highly uniform thickness in areas larger than 20 x 20 mu m(2). The superconducting critical temperature Tc is suppressed from 6.6 K to approximate to 3.0 K when the thickness decreases from 40 nm to 5 nm. The residual-resistivity ratio is slightly smaller than 1 for all the films, which indicates very short electronic mean free path. The films are in the superconducting dirty limit with upper critical field H-c2 approximate to 12 T for films with thickness of 40 nm, and 9 T for films with thickness of 10 nm. In addition, from the critical current densities jc in the vortex-free state, we estimate a penetration depth lambda(0) approximate to (800 +/- 50) nm and a thermodynamic critical field H-c (0) = (500 +/- 80 Oe). (C) 2017 Elsevier B.V. All rights reserved.