SUPERCONDUCTING PROPERTIES AND NORMAL-STATE RESISTIVITY OF SINGLE-CRYSTAL NBN FILMS PREPARED BY A REACTIVE RF-MAGNETRON SPUTTERING METHOD

In this letter, we report some superconducting properties and normal-state resistivities of single-crystal NbN films prepared by a reactive rf-magnetron sputtering method. It was found that the prepared single-crystal NbN films have T(c)'s above 16 K, normal-state resistivities in the range from 12.2 to 14.3-mu-OMEGA cm (at 20 K), and magnetic penetration depths in the range from 93 to 100 nm (at 4.2 K). From a temperature dependence of the upper critical magnetic field for a single-crystal NbN film, the zero-temperature Ginzburg-Landau coherence length xi(GL) (0) for the film was calculated to be 6.9 nm.