METASTABLE NITRIDE SYNTHESIS BY PULSED-LASER DEPOSITION - A NEW PHASE IN THE NBNX SYSTEM

Pulsed laser deposition (PLD) has been used to grow a series of NbNx (0 less than or equal to x less than or equal to 1.2) thin-film materials, including a new superconducting phase. The structural and electrical properties of the NbN, films were characterized. Structural analysis of the new NbN phase indicates that it is stabilized by heteroepitaxial growth on (100) MgO and is shown to be a primitive cubic distortion from the typical B1, or rock-salt structure. In addition, the NbN phase has a higher superconducting critical temperature and a larger lattice parameter when compared with films of B1-NbN. Growth of this new phase demonstrates that the nonequilibrium synthesis properties of PLD can be used to deposit new, metastable materials. (C) 1995 Academic Press, Inc.