Temporal Stability of Y–Ba–Cu–O Nano Josephson Junctions from Ion Irradiation

Abstract

We investigate the temporal stability of YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> Josephson junctions created by ion irradiation through a nanoscale implant mask fabricated using electron beam lithography and reactive ion etching. A comparison of current-voltage characteristics measured for junctions after fabrication and eight years of storage at room temperature show a slight decrease in critical current and increase in normal state resistance consistent with broadening of the weak link from diffusion of defects. Shapiro step measurements performed eight years after fabrication reveal that device uniformity is maintained and is strong evidence that these devices have excellent temporal stability for applications.