Characteristics of Double-junction of High-$\textrm{T}_{c}$ Superconducting $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$ Step-edge Junctions

고온 초전도 $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$ 계단형 모서리 접합의 이중접합 특성

  • Hwang, Jun-Sik (Department of Materials Engineering, Chungnam National University Daeduk Science Town) ;
  • Seong, Geon-Yong (Electronics and Telecommunications Research Institute) ;
  • Gang, Gwang-Yong (Electronics and Telecommunications Research Institute) ;
  • Yun, Sun-Gil (Department of Materials Engineering, Chungnam National University Daeduk Science Town) ;
  • Lee, Gwang-Ryeol (Thin Film Research Center, Korea Institute if Science and Technology)
  • 황준식 (충남대학교 재료공학과) ;
  • 성건용 (한국전자통신연구원) ;
  • 강광용 (한국전자통신연구원) ;
  • 윤순길 (충남대학교 재료공학과) ;
  • 이광렬 (한국과학기술연구원 박막기술연구센터)
  • Published : 1999.01.01

Abstract

We have fabricated high-$\textrm{T}_c$ superconducting $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$(YBCO) grain boundary junctions at a step-edge on (001) $\textrm{SrTiO}_3$(STO) substrates. A diamond-like carbon (DLC) film grown by plasma enhanced chemical vapor deposition were used as an ion milling mask to make steps on the STO (100) single crystal and was removed by an oxygen reactive ion etch process. The c-axis oriented YBCO and TO thin films were deposited epitaxially on the STO substrate with a step-edge by pulsed laser deposition. The grain boundary junctions were formed at the top and the bottom of the step. The junctions worked at temperatures above 77 K, and had I\ulcornerR\ulcorner products of 7.5mV at 16K and 0.3 mV at 77K, respectively. The I-V characteristics of these junctions showed the shape of the two noisy resistively shunted junction model.

(001) $\textrm{SrTiO}_3$(STO) 기판위에 고온초전도 $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$(YBCO)박막을 이용한 계단형 모서리 임계접합을 제조하였다. STO (100) 단결정 기판위에 계단형 모서리(step-edge)를 제작하기 위한 이온밀링 마스크로 plasma enhanced chemical vapor deposition방법으로 증착된 diamond-like carbon (DLC) 박막을 사용하였고, oxygen reactive ion etch 방법으로 건식식각하였다. 이렇게 제작된 계단형 모서리 기판위에 c-축 수직한 YBCO 박막과 STO박막을 pulsed laser deposition방법으로 에피텍셜하게 증착하였다. 계단의 상층과 하층에서 모두 임계가 형성되었으며 이 접합의 임계온도는 77 K 이상이었고 16K에서 $\textrm{I}_{c}\textrm{R}_{n}$products가 7.5mV, 77 K에서 0.3mV의 값을 나타내었다. 이들 전류-전압 특성은 two noisy resistively shunted Josephson junction 모델을 잘 만족하였다.

Keywords

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