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Low-Leakage Superconducting Tunnel Junctions with a Single-Crystal Al2O3 Barrier



Seongshik Oh, Katarina Cicak, Kevin Osborn, Raymond Simmonds, David P. Pappas, Robert Mcdermott, Ken B. Cooper, Matthias Steffen, John M. Martinis


We have developed a two-step growth scheme for single-crystal Al2O3 tunnel barriers. The barriers are epitaxially grown on single-crystal rhenium (Re) base electrodes that are grown epitaxially on a sapphire substrate, while polycrystalline Al is used as the top electrode. We show that, by first growing an amorphous Al oxide layer at room temperature and crystallizing it at a high temperature in oxygen environment, a morphologically intact single-crystal Al2O3 layer is obtained. Tunnel junctions fabricated from these trilayers show very low subgap leakage current with a quality factor of 1200. This leakage-free single-crystal Al2O3 junction has opened a new venue for coherent quantum devices.
Superconductor Science and Technology


Al2O3, Epitaxy, Tunnel Junction


Oh, S. , Cicak, K. , Osborn, K. , Simmonds, R. , Pappas, D. , Mcdermott, R. , Cooper, K. , Steffen, M. and Martinis, J. (2005), Low-Leakage Superconducting Tunnel Junctions with a Single-Crystal Al2O3 Barrier, Superconductor Science and Technology, [online], (Accessed June 15, 2024)


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Created September 4, 2005, Updated October 12, 2021