NbN/TaN/sub x//NbN SNS Josephson junctions by pulsed laser deposition

We have made NbN/TaN/sub x//NbN Josephson junctions with nonhysteretic I-V characteristics that may have potential application for single-flux-quantum logic or SQUID magnetometers. The trilayer growth was done in-situ using pulsed laser deposition. The resistivity of the TaN/sub x/ was varied by the N/sub 2/ pressure during growth from a few hundred micro-ohm-cm at low pressure to a few hundred milli-ohm-cm at pressures up to 300 mTorr. The films were characterized using Rutherford backscattering, X-ray diffraction, and atomic force microscopy. Junction processing was done in the usual trilayer technology. The fabricated Josephson junctions show I/sub c/R/sub n/ values >0.3 mV at 4.2 K. We also observed that at a high laser fluence, NbN films with low a real particulate density and T/sub c//spl sim/16.2 K could be grown on 25/spl deg/C substrates.