STRUCTURAL AND SUPERCONDUCTING PROPERTIES OF ARTIFICIALLY SUPERSTRUCTURED MON-TIN FILMS

Superconducting artificially superstructured films (ASFs) composed of MoN and TiN have been prepared by an alternate reactive deposition method. Alternate layers of MoN and TiN were epitaxially grown on MgO(100) single-crystal substrates. Those ASFs with the periodicities of [MoN(0.4 nm)/TiN(0.4nm)], [MoN(0.2 nm)/TiN(3.4 nm)], and [MoN(2.4 nm)/TiN(0.2 nm)] were successfully synthesized. It was confirmed that the precise thickness of ASFs could be controlled on the atomic level. Average lattice constants of ASFs were calculated from the positions of satellite peaks observed in x-ray diffraction. Structural analyses indicate the formation of a single B1-MoN phase when conditions are optimized. ASFs containing B1-MoN layers showed lower superconducting transition temperatures (Tc 's) than those of ASFs with γ-Mo2N. A few probable reasons for the lower Tc are discussed.