中国物理B ›› 2008, Vol. 17 ›› Issue (8): 3083-3086.doi: 10.1088/1674-1056/17/8/052

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Fabrication of high-quality submicron Nb/Al--AlOx/Nb tunnel junctions

于海峰, 曹文会, 朱晓波, 杨海方, 于洪伟, 任育峰, 顾长志, 陈赓华, 赵士平   

  1. Beijing National Laboratory for Condensed Matter Physics,Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
  • 收稿日期:2008-01-16 修回日期:2008-03-25 出版日期:2008-08-20 发布日期:2008-08-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10474129 and 10534060) and the Ministry of Science and Technology of China (Grant Nos 2006CB601007 and 2006CB921107).

Fabrication of high-quality submicron Nb/Al--AlOx/Nb tunnel junctions

Yu Hai-Feng(于海峰), Cao Wen-Hui(曹文会), Zhu Xiao-Bo(朱晓波), Yang Hai-Fang(杨海方), Yu Hong-Wei(于洪伟), Ren Yu-Feng (任育峰), Gu Chang-Zhi(顾长志), Chen Geng-Hua(陈赓华), and Zhao Shi-Ping(赵士平)†   

  1. Beijing National Laboratory for Condensed Matter Physics,Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
  • Received:2008-01-16 Revised:2008-03-25 Online:2008-08-20 Published:2008-08-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10474129 and 10534060) and the Ministry of Science and Technology of China (Grant Nos 2006CB601007 and 2006CB921107).

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摘要： Nb/Al--AlO$_x$/Nb tunnel junctions are often used in the studies of macroscopic quantum phenomena and superconducting qubit applications of the Josephson devices. In this work, we describe a convenient and reliable process using electron beam lithography for the fabrication of high-quality，submicron-sized Nb/Al--AlO$_x$/Nb Josephson junctions. The technique follows the well-known selective Nb etching process and produces high-quality junctions with $V_m$=100\,mV at 2.3 K for the typical critical current density of 2.2\,kA/cm$^2$, which can be adjusted by controlling the oxygen pressure and oxidation time during the formation of the tunnelling barrier. We present the results of the temperature dependence of the sub-gap current and in-plane magnetic-field dependence of the critical current, and compare them with the theoretical predictions.

关键词: Nb junctions, fabrication, superconducting qubit, macroscopic quantum phenomena

Abstract: Nb/Al--AlO$_x$/Nb tunnel junctions are often used in the studies of macroscopic quantum phenomena and superconducting qubit applications of the Josephson devices. In this work, we describe a convenient and reliable process using electron beam lithography for the fabrication of high-quality，submicron-sized Nb/Al--AlO$_x$/Nb Josephson junctions. The technique follows the well-known selective Nb etching process and produces high-quality junctions with $V_m$=100 mV at 2.3 K for the typical critical current density of 2.2 kA/cm$^2$, which can be adjusted by controlling the oxygen pressure and oxidation time during the formation of the tunnelling barrier. We present the results of the temperature dependence of the sub-gap current and in-plane magnetic-field dependence of the critical current, and compare them with the theoretical predictions.

Key words: Nb junctions, fabrication, superconducting qubit, macroscopic quantum phenomena

中图分类号:  (Tunneling phenomena; Josephson effects)

  • 74.50.+r
74.25.Sv (Critical currents) 74.78.Fk (Multilayers, superlattices, heterostructures)