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Superconducting Microbridge Junctions Fabricated using Focused Ion Beams

Giuseppe Carlo Tettamanzi, Chris I. Pakes, Alessandro Potenza, Christopher H. Marrows, Steven Prawer, David N. Jamieson

Published Jan 1, 2006• 4 citations
Publisher

Abstract

Sub-micron superconducting electronic devices may play a role in the realisation of proposed architectures for quantum computing and metrology. Further miniaturisation of superconducting electronics relies on the ability to fabricate the basic building block, the Josephson junction, on the scale of the superconducting coherence length, with sufficient accuracy that the junction characteristics may be controlled. Making use of focused ion beam technology to fabricate thin-film Nb microbridge devices, we examine the evolution of device characteristics with dimension, focusing on control of the critical current and suppression of superconductivity due to phase-slip behaviour.

DOI
10.1109/iconn.2006.340625

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Sub-micron superconducting electronic devices may play a role in the realisation of proposed architectures for quantum computing and metrology. Further miniaturisation of superconducting electronics relies on the ability to fabricate the basic building block, the Josephson junction, on the scale of the superconducting coherence length, with sufficient accuracy that the junction characteristics may be controlled. Making use of focused ion beam technology to fabricate thin-film Nb microbridge devices, we examine the evolution of device characteristics with dimension, focusing on control of the critical current and suppression of superconductivity due to phase-slip behaviour.
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Controlling the Interface Properties of Submicrometric Nb/A– AlOx\hbox{AlO}_{\rm x}AlOx​–Nb Josephson Junctions
Submicron Josephson devices are of a particular interest to the emerging field of quantum information, nanosized superconducting quantum interference devices (nano-SQUID) fabrication, AC voltage synthesis circuits for quantum metrology, etc. In this paper, we report on the development of our technology for producing non-hysteretic Nb/A-AlOx-Nb four-layered junctions with a diverse range of submicron dimensions, based on the focused ion beam (FIB) sculpting technique. We observed essential modifications of the main electrical characteristics as a result of the shrinking of the junction area, and relate them to the changes of the buried Nb/Al interface. We show that the electrical parameters-versus-temperature dependence can provide information on the quality of the junction interfaces. This aspect could be useful to better control of the entire fabrication process, allowing a further large-scale integration of Josephson nanodevices with improved transport characteristics.
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