nctions with Integrated ~~a~~u~0~ ~o~nd planes

We have fabricated high-T, SNS weak links in an edge geometry with integrated YBa,Cu,Q, (YBCQ) groundplanes and SrTiQ, insulators, using a process which incorporates six epitaxial layers, including a Co- doped-YBCQ normal-metal interlayer. The SNS edge junctions were produced using films deposited by both off-axis sputtering and pulsed laser deposition. These devices exhibit tight J, spreads and high I,R, products in a current density regime well-suited for SFQ circuit fabrication. We also describe results on SNS junctions fabricated in a novel "slot" geometry, designed to reduce junction and interconnect inductances. I. INTRODUCTION Single Flux Quantum (SFQ) logic offers the promise of 10 GHz operation coupled with microwatt power dissipation at the logic gate level. Realization of this potential requires the fabrication of high quality Joseph- son junctions in a multilevel epitaxial process. In particular, junctions with high critical-current - normal- state-resistance (I&") products (>200 pV), tight critical current spreads (pulsed laser deposition process, alternate multilayer processing schemes, and recent results on the effect of edge angle variations on device properties. We also present new electrical data for SNS junctions with and without groundplanes with emphasis on devices with critical currents suitable for SFQ circuits. Finally we show results on a novel "slot junction" geometry, which enables the fabrication of lower inductance junctions and interconnects.