Josephson junctions that use co-sputtered amorphous Nb-Si barriers can be made with a wide variety of electrical properties depending on both the thickness of the barrier and its ratio of Nb to Si. Critical current density (Jc), specific capacitance (Cs), and normal resistance (Rn) can be reliably selected within wide ranges by choosing both the barrier thickness and the Nb concentration. Metallic barriers near the metal-insulator transition are ideal for Josephson voltage standards as they have relatively high IcRn products (where Ic is the critical current) and are non-hysteretic and highly reproducible. More insulating junctions, with thinner barriers have IcRn products greater than 1 mV and Jc values up to 60 kA/cm2 may be useful for superconductive digital electronics. Recent improvements to our deposition system have allowed us to obtain higher values of Jc and better uniformity across the wafer.
Proceedings Title: International Superconductive Electronics Conference - Extended Abstracts
Conference Dates: June 15-19, 2009
Conference Location: Fukuoka, -1
Conference Title: International Superconductive Electronics Conference
Pub Type: Conferences
voltage standard, Josephson junctions, superconductive electronics