Nb-Oxide-Pb Tunnel Junctions Fabricated Using CF4 Cleaning Process. (III) Preparation of Planar dc SQUID

Abstract
This paper discusses the preparation of thin-film planar dc superconducting quantum interference devices (SQUIDs). Nb-oxide-Pb tunnel junctions fabricated using CF4 cleaning process (CFCP) and Pd thin-film shunt resistor were employed. It was demonstrated that the two junctions in a SQUID have symmetrical and wellcontrolled junction parameters. Pd adhesion with oxidized Si could be improved by ultrathin Zr underlayers. The Pd films allowed good controt of the sheet resistance. The SQUIDs are very reliable in regard to room-temperature storage and thermal cycling.