METASTABLE NITRIDE SYNTHESIS BY PULSED-LASER DEPOSITION - A NEW PHASEIN 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 materia ls, including a new superconducting phase. The structural and electric al properties of the NbN, films were characterized. Structural analysi s of the new NbN phase indicates that it is stabilized by heteroepitax ial growth on (100) MgO and is shown to be a primitive cubic distortio n from the typical B1, or rock-salt structure. In addition, the NbN ph ase has a higher superconducting critical temperature and a larger lat tice 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 P ress, Inc.