Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction

Ridderbos, Joost; Brauns, Matthias; Li, Ang; Bakkers, Erik P. A. M.; Brinkman, Alexander; Wiel, Wilfred G. van der; Zwanenburg, Floris A.

doi:10.1103/physrevmaterials.3.084803

Cited by 26 publications

(31 citation statements)

References 73 publications

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“…The observation of a tunable superconducting proximity effect in Ge/Si core/shell NWs was reproduced in more recent experiments using not only Al 74,183,217 but also NbTiN 185 superconducting contacts. The high transparency of the S-Sm contacts was further confirmed by tunnel spectroscopy measurements 218 , which revealed an induced superconducting gap containing only a small density of quasiparticle states.…”

Section: Superconductor-semiconductor Hybridssupporting

confidence: 52%

The germanium quantum information route

et al. 2020

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Section: Superconductor-semiconductor Hybridssupporting

confidence: 52%

The germanium quantum information route

et al. 2020

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“…To overcome these limitations, material combinations with no intermetallic phase formation, such as the Al-Ge system, enabling true metal-semiconductor heterostructures with abrupt metal-semiconductor interfaces received a considerable amount of attention. 12,13,14,15,16,17 Within this paper, we apply quasi 1D…”

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confidence: 99%

Highly Transparent Contacts to the 1D Hole Gas in Ultrascaled Ge/Si Core/Shell Nanowires

et al. 2019

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Semiconductor-superconductor hybrid systems have outstanding potential for emerging high performance nanoelectronics and quantum devices. However, critical to their successful application is the fabrication of high quality and reproducible semiconductor-superconductor interfaces. Here, we realize and measure axial Al-Ge-Al nanowire heterostructures with atomically precise interfaces, enwrapped by an ultra-thin epitaxial Si layer further denoted as Al-Ge/Si-Al nanowire heterostructures. The heterostructures were synthesized by a thermally induced exchange reaction of single-crystalline Ge/Si core/shell nanowires and lithographically defined Al contact pads. Applying this heterostructure formation scheme enables self-aligned quasi one-dimensional crystalline Al leads contacting ultra-scaled Ge/Si segments with contact transparencies greater than 98%. Integration into back-gated field-effect devices and continuous scaling beyond lithographic limitations allows us to exploit the full potential of the highly transparent contacts to the 1D hole gas at the Ge-Si interface. This leads to the observation of ballistic transport as well as quantum confinement effects up to temperatures of 150 K. Low temperature measurements reveal proximity-induced superconductivity in the Ge/Si core/shell nanowires. The realization of a Josephson field-effect transistor allows us to study the subharmonic energy-gap structure caused by multiple Andreev reflections. Most importantly, the absence of a quantum dot regime indicates a hard superconducting gap originating from the highly transparent contacts to the 1D hole-gas,

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“…Thus, the frequency, as well as the average velocity of the chain, are locked. There emerge Shapiro steps which one can compare with experimental results [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Discussionmentioning

confidence: 99%

“…Shapiro steps are reported in the observation of different experiments [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. We concentrate here on the emergence of such steps in calculations with the FK model with periodic boundary conditions (PBC) [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 96%

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Description of Shapiro steps on the potential energy surface of a Frenkel–Kontorova model Part I: The chain in a variable box

Quapp

Bofill

2021

Eur. Phys. J. B

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We explain the vibrations of a Frenkel–Kontorova (FK) model under Shapiro steps by the action of an external alternating force. We demonstrate Shapiro steps for a case with soft ‘springs’ between an 8-particles FK chain. Shapiro steps start with a single jump over the highest $$\hbox {SP}_4$$ SP 4 in the global valley through the PES. They finish with doubled, and again doubled oscillations. We study in this part I a traditional FK model with periodic boundary conditions.

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Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction

Cited by 26 publications

References 73 publications

The germanium quantum information route

The germanium quantum information route

Highly Transparent Contacts to the 1D Hole Gas in Ultrascaled Ge/Si Core/Shell Nanowires

Description of Shapiro steps on the potential energy surface of a Frenkel–Kontorova model Part I: The chain in a variable box

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