Selective niobium anodization process for fabricating Josephson tunnel junctions

Kröger, H.; Smith, L. N.; Jillie, D. W.

doi:10.1063/1.92672

Cited by 305 publications

(70 citation statements)

References 9 publications

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“…The trilayers were patterned with the geometry of the base electrode by reactive ion etching of the Nb layers and chemical etching of the Al layer. The area of the junctions was defined by the selective niobium anodization process, 9 in which part of the top Nb layer in the region surrounding the junction is anodized. Finally, after a sputter cleaning of the top electrode surface, a Nb wiring film was deposited and patterned by lift-off.…”

Section: Methodsmentioning

confidence: 99%

Model for the fine structure of zero field steps in long Josephson tunnel junctions and its comparison with experiment

Barbara

Monaco

Ustinov

1996

Journal of Applied Physics

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The single fluxon dynamics in the resonant regime has been investigated on high-quality low-loss Nb/Al–AlOx/Nb window Josephson tunnel junctions. A new model accounting for the fine structure of zero field steps in linear junctions is proposed. Depending on the fluxon velocity and on the junction losses, resonances may occur between the fluxon and the plasma waves corresponding to different wave numbers. This mechanism relies on a single proposition that the fluxon experiences an acceleration approaching the nonideal boundaries of the junction. We find good agreement between theory, numerical simulations, and experiments. The presence of the idle region has been proved to play a determinant role for the occurrence of the fine structure.

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Section: Methodsmentioning

confidence: 99%

Model for the fine structure of zero field steps in long Josephson tunnel junctions and its comparison with experiment

Barbara

Monaco

Ustinov

1996

Journal of Applied Physics

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“…Square junction areas (L Â L ¼ 50 Â 50 lm 2 ) of Nb/Al-oxide/Nb structures are defined by the selective niobium anodization process. 21 We can use three pairs of Helmholtz coils (H x coils, H y coils, and H z coils). The 2-D magnetic field dependences of current-voltage characteristics of the superconducting junction in liquid helium are measured by using two pairs of Helmholtz coils (H x coils and H y coils), where the directions H x and H y are parallel to the edges of this square junction area as shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Two-dimensional magnetic field dependence of Josephson current and resonant current steps at finite voltage of square shape superconducting tunnel junctions

Nakayama

Abe

Watanabe

2012

Journal of Applied Physics

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In this article, modulation characteristics of Josephson current through square shape niobium/aluminum-oxide/niobium superconducting junction by two-dimensional scanning of external magnetic field have been studied. Two pairs of Helmholtz coils are controlled by two current sources with general purpose interface bus system to obtain the magnetic field dependence automatically. The distribution of Josephson current density inside the square junction area is obtained. The 2-D magnetic field dependences of the resonant current steps of the current-voltage characteristics of the Nb/Al-oxide/Nb tunnel junction have also been measured using the junction voltage as the parameter.

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“…Subsequently, the junction shapes were defined with the SNAP process [9], with anodization voltages of 47 V and 57 V, giving Nb205 thicknesses of 108 nm and 131 nm for HG#4 and HG#10, respectively. On HG#4 we patterned square, diamondshaped, "1 + cosine" shaped, and quartic-shaped junctions, and on HG#10 we patterned quartic junctions and quartic junctions with various internal structures.…”

Section: Sample Preparationmentioning

confidence: 99%

Field dependence on the Josephson current and Fiske resonances in specially shaped Josephson junctions

Gijsbertsen

Houwman

Klopman

et al. 1995

Physica C: Superconductivity

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We investigated the magnetic-field dependence of the Josephson current and Fiske resonances in specially shaped Josephson junctions. In order to be able to use junctions for high-resolution X-ray spectroscopy, a very good suppression of the sidelobes of both the Josephson current and the Fiske resonances must be achieved.In a theoretical argument we show that a properly chosen junction shape leads to the sidelobe suppression of both the critical current and Fiske resonance amplitudes.The Josephson current and Fiske resonance amplitudes were measured as a function of the magnetic field, for junctions fabricated in Nb/AI technology. As expected, a very good sidelobe suppression was obtained for quartic-shaped junctions. For junctions with anodized structures within the tunneling area, the shape of the internal structures is reflected in the field dependence of both the Josephson current and the Fiske resonances. Finally, Fiske modes in these junctions have been imaged with low-temperature scanning electron microscopy, and we conclude that a quartic junction can be approximated by a rectangle, to describe the lower-order Fiske modes, whereas the high-order modes are specific to the exact shape of the junction.

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Selective niobium anodization process for fabricating Josephson tunnel junctions

Cited by 305 publications

References 9 publications

Model for the fine structure of zero field steps in long Josephson tunnel junctions and its comparison with experiment

Model for the fine structure of zero field steps in long Josephson tunnel junctions and its comparison with experiment

Two-dimensional magnetic field dependence of Josephson current and resonant current steps at finite voltage of square shape superconducting tunnel junctions

Field dependence on the Josephson current and Fiske resonances in specially shaped Josephson junctions

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