Influence of target processing on properties of NdBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films grown by PLD: comparison of sintered ceramic and single crystal targets

The influence of target processing on properties of deposited NBCO films, including superconductivity, epitaxial structure, and surface morphology has been systematically investigated between a large Nd123 single crystal and slightly Ba-rich Nd/sub 1-x/Ba/sub 2+x/Cu/sub 3/O/sub 7-/spl delta// (x=0.00, 0.03, 0.05, and 0.10) sintered ceramic targets. The films with excellent superconductivity and good crystallinity were grown on SrTiO/sub 3/ [100], LaAlO/sub 3/ [100], and NdGaO/sub 3/ [110] substrates by pulsed laser deposition (PLD). At optimized deposition conditions, T/sub c0/ of 90-94 K is routinely achieved. The critical current density J/sub c/ is >3/spl times/10/sup 6/ A/cm/sup 2/ at 77 K. The films deposited from sintered targets exhibit a typical droplet density of 10/sup 6/-10/sup 7//cm/sup 2/ on the film surface. However, the films deposited from the single crystal target show smooth nearly droplet-free surface morphology. Our results indicate that single crystal targets are more suitable for the growth of smooth high-T/sub c/ superconducting films by PLD.