Exploratory Research for a High Temperature Superconducting Integrated Circuit

Abstract : The objective of this effort was the exploration investigation of the molecular-beam-epitaxy-trilayer Josephson Junction process under development by VARIAN Corporation. Under this effort, Stanford University provided fundamental materials characterization to understand and improve the surfaces and interfaces of the thin film structures. HYPRES Inc. provided an independent assessment of the junctions produced by Varian and addressed the possibilities of rapid single fluxquantum (RSFQ) circuit designs. The material system chosen for this investigation was Bismuth-Strontium Calcium-Copper-Oxide (BSSCO). The Josephson Junction character of the devices was confirmed by the observation of microwave induced (Shapior) steps in the I-V curves. Contract resistance by three orders of magnitude by modulation doping the top few molecular layers of the upper superconductive electrode. The desired properties to warrant RSFQ circuit fabrication were not obtained. A material system with a higher Josephson Junction critical temperature and higher critical current is necessary for circuits. Microwaves Superconductors Josephsons junctions.