MAGNETIC PENETRATION DEPTHS AND NORMAL-STATE RESISTIVITIES OF EPITAXIAL AND POLYCRYSTALLINE NBCXN1-X FILMS

We have studied the magnetic penetration depth-lambda and the normal-state resistivity-rho of epitaxial and polycrystalline NbCxN1-x films as a function of film thickness t and sputtering gas pressure P during the deposition of the films. It was found that lambda(approximately 200 nm) and rho(approximately 50-mu-OMEGA.cm) of epitaxial films are almost independent of P and t, while lambda(> 300 nm) and rho(> 110-mu-OMEGA.cm) of polycrystalline films increase considerably with increasing P(> 2 Pa) or decreasing t(< 80 nm). The pressure and thickness dependence of lambda and rho of polycrystalline films can be explained by a model of Josephson coupling between grains.