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Aluminum Nitride Tunnel Barrier Formation with Low-Energy Nitrogen Ion Beams

Published online by Cambridge University Press:  03 March 2011

Anupama B. Kaul
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
Alan W. Kleinsasser
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
Bruce Bumble
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
Henry G. LeDuc
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
Karen A. Lee
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
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Abstract

We report the use of low-energy nitrogen ion beams to form ultra-thin (<2 nm) layers of AlNx to act as tunnel barriers in Nb/Al–AlNx/Nb Josephson junctions. We fabricated reproducible, high-quality devices with independent control of the ion energy and dose, enabling exploration of a wide parameter space. Critical current density Jc ranged from 550 to 9400 A/cm2 with subgap-to-normal resistance ratios from 50 to 12.6. The spatial variation of ion-current density was roughly correlated with Jc over a large-area on a Si substrate. The junctions were stable on annealing up to temperatures of at least 200 °C. This technique could be applied to form other metal nitrides at room temperature for device applications where a high degree of control is desired.

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Articles
Copyright
Copyright © Materials Research Society 2005

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References

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