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Title: Tunable Nitride Josephson Junctions.

Abstract

We have developed an ambient temperature, SiO 2/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the Ta xN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlO x barriers for low - power, high - performance computing.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1412824
Report Number(s):
SAND-2017-12990
659307
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Missert, Nancy A., Henry, Michael David, Lewis, Rupert M., Howell, Stephen W., Wolfley, Steven L., Brunke, Lyle Brent, and Wolak, Matthaeus. Tunable Nitride Josephson Junctions.. United States: N. p., 2017. Web. doi:10.2172/1412824.
Missert, Nancy A., Henry, Michael David, Lewis, Rupert M., Howell, Stephen W., Wolfley, Steven L., Brunke, Lyle Brent, & Wolak, Matthaeus. Tunable Nitride Josephson Junctions.. United States. doi:10.2172/1412824.
Missert, Nancy A., Henry, Michael David, Lewis, Rupert M., Howell, Stephen W., Wolfley, Steven L., Brunke, Lyle Brent, and Wolak, Matthaeus. Fri . "Tunable Nitride Josephson Junctions.". United States. doi:10.2172/1412824. https://www.osti.gov/servlets/purl/1412824.
@article{osti_1412824,
title = {Tunable Nitride Josephson Junctions.},
author = {Missert, Nancy A. and Henry, Michael David and Lewis, Rupert M. and Howell, Stephen W. and Wolfley, Steven L. and Brunke, Lyle Brent and Wolak, Matthaeus},
abstractNote = {We have developed an ambient temperature, SiO2/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the TaxN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlOx barriers for low - power, high - performance computing.},
doi = {10.2172/1412824},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 01 00:00:00 EST 2017},
month = {Fri Dec 01 00:00:00 EST 2017}
}

Technical Report:

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  • Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showingmore » good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q {approx} 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement.« less
  • Radiation emitted by Nb --Nb point contact Josephson junctions at frequencies up to 30 cm/sup -1/ was studied. Spectroscopic measurements on solids have been made using this source. (auth)