Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits

Fritz, S., Seiler, A., Radtke, L., Schneider, R., Weides, M. , Weiß, G. and Gerthsen, D. (2018) Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits. Scientific Reports, 8, 7956. (doi: 10.1038/s41598-018-26066-4) (PMID:29785054) (PMCID:PMC5962554)

Abstract

This work is concerned with Al/Al-oxide(AlOx)/Al-layer systems which are important for Josephson-junction-based superconducting devices such as quantum bits. The device performance is limited by noise, which has been to a large degree assigned to the presence and properties of two-level tunneling systems in the amorphous AlOx tunnel barrier. The study is focused on the correlation of the fabrication conditions, nanostructural and nanochemical properties and the occurrence of two-level tunneling systems with particular emphasis on the AlOx-layer. Electron-beam evaporation with two different processes and sputter deposition were used for structure fabrication, and the effect of illumination by ultraviolet light during Al-oxide formation is elucidated. Characterization was performed by analytical transmission electron microscopy and low-temperature dielectric measurements. We show that the fabrication conditions have a strong impact on the nanostructural and nanochemical properties of the layer systems and the properties of two-level tunneling systems. Based on the understanding of the observed structural characteristics, routes are suggested towards the fabrication of Al/AlOx/Al-layers systems with improved properties.

• Item Type: Articles
• Additional Information: The authors acknowledge support by Deutsche Forschungsgemeinschaf and Open Access Publishing Fund of Karlsruhe Institute of Technology.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Weides, Professor Martin
• Authors: Fritz, S., Seiler, A., Radtke, L., Schneider, R., Weides, M., Weiß, G., and Gerthsen, D.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Scientific Reports
• Publisher: Nature Research
• ISSN: 2045-2322
• ISSN (Online): 2045-2322
• Copyright Holders: Copyright © 2018 The Authors
• First Published: First published in Scientific Reports 8: 7956
• Publisher Policy: Reproduced under a Creative Commons License