Sub-gap leakage current of Nb/Al-AlOx-Al/Nb Josephson junction fabricated using facing target sputtering

摘要

Nb and Al films in the Nb/AlOx/Nb junction structure have been deposited using facing target sputtering technique applied with DC power. In this sputtering technique, the gamma electrons generated in the plasma are retained and reciprocated between a pair of targets and those hardly do damage to the junction interface during the deposition. A SiO2 film has been also deposited using the same sputtering applied with RF power. An anodization process is used for the fabrication process. Fabricated junctions have indicated the I-V characteristics with small sub-gap leakage current (0.13 pA/mu m(2) at 0.49 K). We think it is effective for both the facing target sputtering technique and the anodization process to obtain the junction with small sub-gap leakage current. (c) 2007 Published by Elsevier B.V.