Development of thin film multilayer structures with smooth surfaces for HTS SFQ circuits

被引：30

作者：

Wakana, H ^{[1
]}

Adachi, S ^{[1
]}

Kamitani, A ^{[1
]}

Nakayama, K ^{[1
]}

Ishimaru, Y ^{[1
]}

Tarutani, Y ^{[1
]}

Tanabe, K ^{[1
]}

机构：

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

来源：

IEICE TRANSACTIONS ON ELECTRONICS | 2005年 / E88C卷 / 02期

关键词：

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

D O I：

10.1093/ietele/E88-C.2.208

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 fabricated a multilayer structure for single flux quantum (SFQ) circuit application using a high-temperature superconductor (HTS). La-0.2-Y0.9Ba1.9Cu3Ox (La-YBCO) base electrode layers were prepared by a dc or rf magnetron sputtering method. The reproducibility of film quality for dc-sputtered La-YBCO films was better than that for rf-sputtered films, and the dc sputtered films exhibited the average surface roughness R-a less than 1.0 out and a T-c zero value of 88 K. By using the de-sputtered La-YBCO films, a multilayer structure of SrSnO3/La-YBCO/ SrSnO3/La-YBCO on MgO substrate with R-a below 2.0 nm was obtained. Interface-modified ramp-edge junctions with La-0.2-Yb0.9Ba1.9Cu3Ox (La-YbBCO) counter electrodes have been fabricated by using this multilayer structure with dc-sputtered films. The fabricated junctions exhibited RSJ-type I - V characteristics with IcRn products of about 3 mV at 4.2 K. We also obtained a I-sigma I-c spread of 8% for a 1000-junction series-array. The sheet inductance values at 4.2 K for the base and counter electrodes on La-YBCO ground planes were 0.8 pH and 0.7 pH per square, respectively. Operation of several types of elementary SFQ circuits has been successfully demonstrated by using this multilayer structure.

引用

页码：208 / 215

页数：8

共 22 条

[1] Preparation of La-doped Yb-123 thin films for high-Tc devices [J].