Title :
Performance of Josephson array systems related to fabrication techniques and design
Author :
Muller, F. ; Kohlmann, J. ; Hebrank, F.X. ; Weimann, T. ; Wolf, H. ; Niemeyer, J.
Author_Institution :
Physikalisch Tech. Bundesanstalt, Braunschweig, Germany
fDate :
6/1/1995 12:00:00 AM
Abstract :
Arrays of Nb/Al/sub 2/O/sub 3//Nb Josephson tunnel junctions show dc characteristics of high quality when the trilayer is deposited direct on polished Si wafers. Underlayers such as rf-sputtered SiO/sub 2/, can considerably degrade the junction parameters. These results suggest that voltage standard chips should be produced with a cover instead of a groundplane. First results of attenuation measurements on such circuits are presented and discussed. Furthermore, a new and more simple fabrication process without a window-insulating layer and only two photolithographic steps is presented. Arrays of several thousands of junctions showed no problems of any kind with trapped flux.<>
Keywords :
Josephson effect; aluminium compounds; measurement standards; microwave oscillators; niobium; photolithography; strip line components; superconducting device testing; superconducting microwave devices; type II superconductors; Josephson array systems; Josephson tunnel junctions; Nb-AlO-Nb; Si; attenuation measurements; dc characteristics; fabrication process; fabrication techniques; junction parameters; microwave oscillators; photolithographic steps; strip lines; voltage standard chips; window-insulating layer; Attenuation measurement; Circuit testing; Fabrication; Insulation; Lead; Microwave circuits; Microwave technology; Niobium alloys; Voltage; Wiring;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
