Hard Superconducting Gap and Diffusion-Induced Superconductors in Ge–Si Nanowires

Joost Ridderbos, Matthias Brauns, Folkert K. De Vries, Jie Shen, Ang Li, Sebastian Kölling, Marcel A. Verheijen, Alexander Brinkman, Wilfred G. Van Der Wiel, Erik P. A. M. Bakkers, Floris A. Zwanenburg*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

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    Abstract

    We show a hard superconducting gap in a Ge–Si nanowire Josephson transistor up to in-plane magnetic fields of 250 mT, an important step toward creating and detecting Majorana zero modes in this system. A hard gap requires a highly homogeneous tunneling heterointerface between the superconducting contacts and the semiconducting nanowire. This is realized by annealing devices at 180 °C during which aluminum interdiffuses and replaces the germanium in a section of the nanowire. Next to Al, we find a superconductor with lower critical temperature (TC = 0.9 K) and a higher critical field (BC = 0.9–1.2 T). We can therefore selectively switch either superconductor to the normal state by tuning the temperature and the magnetic field and observe that the additional superconductor induces a proximity supercurrent in the semiconducting part of the nanowire even when the Al is in the normal state. In another device where the diffusion of Al rendered the nanowire completely metallic, a superconductor with a much higher critical temperature (TC = 2.9 K) and critical field (BC = 3.4 T) is found. The small size of these diffusion-induced superconductors inside nanowires may be of special interest for applications requiring high magnetic fields in arbitrary direction.
    Original languageEnglish
    Number of pages9
    JournalNano letters
    DOIs
    Publication statusE-pub ahead of print/First online - 26 Nov 2019

    Fingerprint

    Superconducting materials
    Nanowires
    nanowires
    Magnetic fields
    critical temperature
    magnetic fields
    Germanium
    Aluminum
    Temperature
    proximity
    germanium
    Transistors
    transistors
    switches
    Tuning
    tuning
    Switches
    Annealing
    aluminum
    annealing

    Keywords

    • UT-Hybrid-D
    • Superconductor−semiconductor hybrid device

    Cite this

    Ridderbos, Joost ; Brauns, Matthias ; De Vries, Folkert K. ; Shen, Jie ; Li, Ang ; Kölling, Sebastian ; Verheijen, Marcel A. ; Brinkman, Alexander ; Van Der Wiel, Wilfred G. ; Bakkers, Erik P. A. M. ; Zwanenburg, Floris A. / Hard Superconducting Gap and Diffusion-Induced Superconductors in Ge–Si Nanowires. In: Nano letters. 2019.
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    title = "Hard Superconducting Gap and Diffusion-Induced Superconductors in Ge–Si Nanowires",
    abstract = "We show a hard superconducting gap in a Ge–Si nanowire Josephson transistor up to in-plane magnetic fields of 250 mT, an important step toward creating and detecting Majorana zero modes in this system. A hard gap requires a highly homogeneous tunneling heterointerface between the superconducting contacts and the semiconducting nanowire. This is realized by annealing devices at 180 °C during which aluminum interdiffuses and replaces the germanium in a section of the nanowire. Next to Al, we find a superconductor with lower critical temperature (TC = 0.9 K) and a higher critical field (BC = 0.9–1.2 T). We can therefore selectively switch either superconductor to the normal state by tuning the temperature and the magnetic field and observe that the additional superconductor induces a proximity supercurrent in the semiconducting part of the nanowire even when the Al is in the normal state. In another device where the diffusion of Al rendered the nanowire completely metallic, a superconductor with a much higher critical temperature (TC = 2.9 K) and critical field (BC = 3.4 T) is found. The small size of these diffusion-induced superconductors inside nanowires may be of special interest for applications requiring high magnetic fields in arbitrary direction.",
    keywords = "UT-Hybrid-D, Superconductor−semiconductor hybrid device",
    author = "Joost Ridderbos and Matthias Brauns and {De Vries}, {Folkert K.} and Jie Shen and Ang Li and Sebastian K{\"o}lling and Verheijen, {Marcel A.} and Alexander Brinkman and {Van Der Wiel}, {Wilfred G.} and Bakkers, {Erik P. A. M.} and Zwanenburg, {Floris A.}",
    note = "ACS deal",
    year = "2019",
    month = "11",
    day = "26",
    doi = "10.1021/acs.nanolett.9b03438",
    language = "English",
    journal = "Nano letters",
    issn = "1530-6984",
    publisher = "American Chemical Society",

    }

    Hard Superconducting Gap and Diffusion-Induced Superconductors in Ge–Si Nanowires. / Ridderbos, Joost; Brauns, Matthias; De Vries, Folkert K.; Shen, Jie; Li, Ang; Kölling, Sebastian; Verheijen, Marcel A.; Brinkman, Alexander; Van Der Wiel, Wilfred G.; Bakkers, Erik P. A. M.; Zwanenburg, Floris A.

    In: Nano letters, 26.11.2019.

    Research output: Contribution to journalArticleAcademicpeer-review

    TY - JOUR

    T1 - Hard Superconducting Gap and Diffusion-Induced Superconductors in Ge–Si Nanowires

    AU - Ridderbos, Joost

    AU - Brauns, Matthias

    AU - De Vries, Folkert K.

    AU - Shen, Jie

    AU - Li, Ang

    AU - Kölling, Sebastian

    AU - Verheijen, Marcel A.

    AU - Brinkman, Alexander

    AU - Van Der Wiel, Wilfred G.

    AU - Bakkers, Erik P. A. M.

    AU - Zwanenburg, Floris A.

    N1 - ACS deal

    PY - 2019/11/26

    Y1 - 2019/11/26

    N2 - We show a hard superconducting gap in a Ge–Si nanowire Josephson transistor up to in-plane magnetic fields of 250 mT, an important step toward creating and detecting Majorana zero modes in this system. A hard gap requires a highly homogeneous tunneling heterointerface between the superconducting contacts and the semiconducting nanowire. This is realized by annealing devices at 180 °C during which aluminum interdiffuses and replaces the germanium in a section of the nanowire. Next to Al, we find a superconductor with lower critical temperature (TC = 0.9 K) and a higher critical field (BC = 0.9–1.2 T). We can therefore selectively switch either superconductor to the normal state by tuning the temperature and the magnetic field and observe that the additional superconductor induces a proximity supercurrent in the semiconducting part of the nanowire even when the Al is in the normal state. In another device where the diffusion of Al rendered the nanowire completely metallic, a superconductor with a much higher critical temperature (TC = 2.9 K) and critical field (BC = 3.4 T) is found. The small size of these diffusion-induced superconductors inside nanowires may be of special interest for applications requiring high magnetic fields in arbitrary direction.

    AB - We show a hard superconducting gap in a Ge–Si nanowire Josephson transistor up to in-plane magnetic fields of 250 mT, an important step toward creating and detecting Majorana zero modes in this system. A hard gap requires a highly homogeneous tunneling heterointerface between the superconducting contacts and the semiconducting nanowire. This is realized by annealing devices at 180 °C during which aluminum interdiffuses and replaces the germanium in a section of the nanowire. Next to Al, we find a superconductor with lower critical temperature (TC = 0.9 K) and a higher critical field (BC = 0.9–1.2 T). We can therefore selectively switch either superconductor to the normal state by tuning the temperature and the magnetic field and observe that the additional superconductor induces a proximity supercurrent in the semiconducting part of the nanowire even when the Al is in the normal state. In another device where the diffusion of Al rendered the nanowire completely metallic, a superconductor with a much higher critical temperature (TC = 2.9 K) and critical field (BC = 3.4 T) is found. The small size of these diffusion-induced superconductors inside nanowires may be of special interest for applications requiring high magnetic fields in arbitrary direction.

    KW - UT-Hybrid-D

    KW - Superconductor−semiconductor hybrid device

    U2 - 10.1021/acs.nanolett.9b03438

    DO - 10.1021/acs.nanolett.9b03438

    M3 - Article

    JO - Nano letters

    JF - Nano letters

    SN - 1530-6984

    ER -