Effects of aluminum over-layer thickness on characteristics of niobium tunnel junctions fabricated by DC magnetron sputtering

Author

Nakayama, A. ; Nagashima, H. ; Shimada, J. ; Okabe, Y.

Author_Institution

Dept. of Electr. Eng., Kanagawa Univ., Yokohama, Japan

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

2299

Lastpage

2302

Abstract

We have fabricated Nb/AlO/sub x//Nb Josephson tunnel junctions using a sputtering apparatus with a load-lock system. The junctions that had 50 /spl mu/m/spl times/50 /spl mu/m area showed a V/sub m/ value (the product of the critical current and the subgap resistance at 2 mV) as high as 50 mV at a current density of 160 A/cm/sup 2/. Moreover, junctions having different thicknesses of the Al overlayer were concurrently fabricated on one wafer to study the dependence of the current-voltage characteristics on this Al over-layer. The I-V characteristics were also calculated by McMillan´s tunneling model and were compared with the measured I-V characteristics.<>

Keywords

Josephson effect; aluminium; niobium; sputtered coatings; 50 micron; Al; DC magnetron sputtering; McMillan tunneling model; Nb-AlO-Nb; Nb/AlO/sub x//Nb Josephson tunnel junctions; aluminum over-layer; critical current; current density; current-voltage characteristics; fabrication; load-lock; subgap resistance; Aluminum; Artificial intelligence; Current-voltage characteristics; Electrodes; Fabrication; Niobium; Sputtering; Substrates; Superconducting films; Tunneling;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.403045

Filename

403045