Improvement in reproducibility of multilayer and junction process for HTS SFQ circuits

被引：36

作者：

Wakana, H ^{[1
]}

Adachi, S ^{[1
]}

Kamitani, A ^{[1
]}

Nakayama, K ^{[1
]}

Ishimaru, Y ^{[1
]}

Oshikubo, Y ^{[1
]}

Tarutani, Y ^{[1
]}

Tanabe, K ^{[1
]}

机构：

[1] ISTEC, Superconduct Res Lab, Tokyo 1350062, Japan

来源：

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY | 2005年 / 15卷 / 02期

关键词：

high-temperature superconductor; Josephson junction; ramp-edge structure; SFQ circuit;

D O I：

10.1109/TASC.2005.849723

中图分类号：

TM [电工技术]; TN [电子技术、通信技术];

学科分类号：

0808 ; 0809 ;

摘要：

We have developed an HTS multilayer structure including a superconducting ground plane and interface-engineered ramp-edge Josephson junctions for single flux quantum (SFQ) circuits, and tried to improve reproducibility in the multilayer and junction process. We found that one of the crucial factors to improve the reproducibility is use of a ground plane with small average surface roughness (R-a) of typically less than 2 nm and a high T-c above 87 K. By employing La-0.2-Y0.9Ba1.9Cu3Ox (La-YBCO) thin films deposited by dc off-axis magnetron sputtering, such high quality was maintained for 3-month successive use of a ceramic target. Use of such a high-quality ground plane reproducibly led to SrSnO3/La - YBCO/SrSnO3/La - YBCO//MgO multilayer structures with R-a <= 2 nm and 100-junction arrays with 1 - sigma I-c spread of 6-17% at 4.2 K depending on the average I-c level. The run-to-run reproducibility of average junction I-c and sheet inductance of both the base- and counter-electrodes for three samples was +/- 12%, +/- 3.0%, and +/- 3.4%, respectively, which are substantially smaller than those previously reported.

引用

页码：153 / 156

页数：4

共 16 条

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