Structural and nanochemical properties of AlOx layers in Al/AlOx/Al -layer systems for Josephson junctions

Fritz, S., Radtke, L., Schneider, R., Luysberg, M., Weides, M. and Gerthsen, D. (2019) Structural and nanochemical properties of AlOx layers in Al/AlOx/Al -layer systems for Josephson junctions. Physical Review Materials, 3(11), 114805. (doi: 10.1103/PhysRevMaterials.3.114805)

Abstract

The structural and nanochemical properties of thin AlOx layers are decisive for the performance of advanced electronic devices. For example, they are frequently used as tunnel barriers in Josephson junction-based superconducting devices. However, systematic studies of the influence of oxidation parameters on structural and nanochemical properties are rare up to now, as most studies focus on the electrical properties of AlOx layers. This study aims to close this gap by applying transmission electron microscopy in combination with electron energy loss spectroscopy to analyze the structural and nanochemical properties of differently fabricated AlOx layers and correlate them with fabrication parameters. With respect to the application of AlOx as tunnel barrier in superconducting Josephson junctions, Al/AlOx/Al-layer systems were deposited on Si substrates. We will show that the oxygen content and structure of amorphous AlOx layers is strongly dependent on the fabrication process and oxidation parameters. Dynamic and static oxidation of Al yields oxygen-deficient amorphous AlOx layers, where the oxygen content ranges from x=0.5 to x=1.3 depending on oxygen pressure and substrate temperature. Thicker layers of stoichiometric crystalline γ−Al2O3 layers were grown by electron-beam evaporation of Al2O3 and reactive sputter deposition.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Weides, Professor Martin
• Authors: Fritz, S., Radtke, L., Schneider, R., Luysberg, M., Weides, M., and Gerthsen, D.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Physical Review Materials
• Publisher: American Physical Society
• ISSN: 2475-9953
• ISSN (Online): 2475-9953
• Published Online: 21 November 2019
• Copyright Holders: Copyright © 2019 American Physical Society
• First Published: First published in Physical Review Materials 3(11):114805
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher