Intrinsic Josephson Junctions in Bi-2212 Thin Films Fabricated by Metal-Organic Decomposition

Abstract

We fabricated a mesa <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10\ \mu{\rm m}\times 10\ \mu{\rm m}$</tex></formula> in area and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\sim$</tex></formula> 150 nm in height on a single grain in a 240-nm <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm Bi}_{2}{\rm Sr}_{2}{\rm CaCu}_{2}{\rm O}_{8+\delta}/{\rm MgO}$</tex></formula> thin-film grown by metal-organic decomposition (MOD) with face-to-face annealing. A multi-branch structure peculiar to intrinsic Josephson junctions (IJJs) was observed in the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I-V$</tex> </formula> characteristics of the fabricated mesa, and this structure was characterized by approximately 100 quasiparticle branches with critical current densities of 1 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm kA/cm}^{2}$</tex> </formula> and voltage-jump intervals of 20 mV. Moreover, the temperature dependence of the critical current was in good agreement with a theoretical result based on <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$c$</tex> </formula> -axis Josephson tunneling in <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$d$</tex></formula> -wave superconductors. These results imply that the thin films grown by MOD have sufficient quality to fabricate IJJs for practical terahertz applications.