Charge transport in InAs nanowire Josephson junctions

Abay, Simon; Persson, Daniel; Nilsson, Henrik; Wu, Fan; Xu, Hongqi; Fogelström, Mikael; Shumeiko, Vitaly; Delsing, Per

doi:10.1103/physrevb.89.214508

Cited by 65 publications

(87 citation statements)

References 47 publications

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“…For instance, the coupling of gate-defined qubits at the nanowire ends via a superconductor has been proposed 2 , but also quantum network structures 5 . Further, gateable nanowire-based Josephson junctions [6][7][8] are in the focus of ongoing research. SC/InAs systems have been predicted to provide the optimal environment for proximity-induced p-wave superconductivity, leading in presence of an external magnetic field to spinless quasiparticles in form of triplet state Cooper pairs within the semiconductor 4,9 .…”

Section: Introductionmentioning

confidence: 99%

MBE growth of Al/InAs and Nb/InAs superconducting hybrid nanowire structures

et al. 2017

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We report on in situ growth of crystalline Al and Nb shells on InAs nanowires. The nanowires are grown on Si(111) substrates by molecular beam epitaxy (MBE) without foreign catalysts in the vapor-solid mode. The metal shells are deposited by electron-beam evaporation in a metal MBE. High quality supercondonductor/semiconductor hybrid structures such as Al/InAs and Nb/InAs are of interest for ongoing research in the fields of gateable Josephson junctions and quantum information related research. Systematic investigations of the deposition parameters suitable for metal shell growth are conducted. In case of Al, the substrate temperature, the growth rate and the shell thickness are considered. The substrate temperature as well as the angle of the impinging deposition flux are explored for Nb shells. The core-shell hybrid structures are characterized by electron microscopy and x-ray spectroscopy. Our results show that the substrate temperature is a crucial parameter in order to enable the deposition of smooth Al layers. Contrary, Nb films are less dependent on substrate temperature but strongly affected by the deposition angle. At a temperature of 200• C Nb reacts with InAs, dissolving the nanowire crystal. Our investigations result in smooth metal shells exhibiting an impurity and defect free, crystalline superconductor/InAs interface. Additionally, we find that the superconductor crystal structure is not affected by stacking faults present in the InAs nanowires.

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Section: Introductionmentioning

confidence: 99%

MBE growth of Al/InAs and Nb/InAs superconducting hybrid nanowire structures

et al. 2017

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“…Owing to these excellent material characteristics and their intrinsic low dimensionality, InAs and InP nanowires have been explored to realize various novel devices and systems, including nanowire field-effect transistors, [1][2][3][4] light emitting devices, [5,6], solar cells, [7][8][9] and superconducting quantum devices. [18][19][20][21] It has also been demonstrated that InAs nanowires exhibit strong electron spin-orbit coupling and these nanowires are desired materials for realization of topological superconducting systems in which Majorana bound states can be present and exploited for topological quantum computation. [22][23][24][25][26][27] Epitaxially grown InAs and InP nanowires can have zincblende lattice structures and are most commonly oriented along 111 crystallographic directions.…”

Section: Introductionmentioning

confidence: 99%

Electronic structures of [1 1 1]-oriented free-standing InAs and InP nanowires

Liao¹,

Luo²,

Chen³

et al. 2016

J. Phys.: Condens. Matter

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We report on a theoretical study of the electronic structures of the [111]-oriented, free-standing, zincblende InAs and InP nanowires with hexagonal cross sections by means of an atomistic sp 3 s * , spin-orbit interaction included, nearest-neighbor, tight-binding method. The band structures and the band state wave functions of these nanowires are calculated and the symmetry properties of the bands and band states are analyzed based on the C3v double point group. It is shown that all bands of these nanowires are doubly degenerate at the Γ-point and some of these bands will split into non-degenerate bands when the wave vector k moves away from the Γ-point as a manifestation of spin-splitting due to spin-orbit interaction. It is also shown that the lower conduction bands of these nanowires all show simple parabolic dispersion relations, while the top valence bands show complex dispersion relations and band crossings. The band state wave functions are presented by the spatial probability distributions and it is found that all the band states show 2π/3-rotation symmetric probability distributions. The effects of quantum confinement on the band structures of the [111]-oriented InAs and InP nanowires are also examined and an empirical formula for the description of quantization energies of the lowest conduction band and the highest valence band is presented. The formula can simply be used to estimate the enhancement of the band gaps of the nanowires at different sizes as a result of quantum confinement.

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“…S. Abay and coworkers in Ref. 34 suggested an alternative mechanism based on the presence of inhomogeneities in the NW. In this scenario, the observed peaks would be related to the sequential appearance of normal domains in the NW as the current is increased.…”

Section: Eletrical Transport Measurementsmentioning

confidence: 99%

Suspended InAs nanowire Josephson junctions assembled via dielectrophoresis

Montemurro¹,

Stornaiuolo²,

Massarotti³

et al. 2015

Nanotechnology

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We present a novel technique for the realization of suspended Josephson junctions based on InAs semiconductor nanowires. The devices are assembled using a technique of drop-casting guided by dielectrophoresis that allows to finely align the nanostructures on top of the electrodes. The proposed architecture removes the interaction between the nanowire and the substrate which is known to influence disorder and the orientation of the Rashba vector. The relevance of this approach in view of the implementation of Josephson junctions based on HighTemperature Superconductors is discussed. INTRODUCTION.Hybrid devices based on low---dimensional materials coupled to superconducting (SC) electrodes emerged in the last years as an ideal platform for the investigation unconventional quantum effects. In these devices the macroscopic quantum correlations typical of SCs can be induced via proximity effect in a wide class of low---dimensional materials such as graphene 1,2 and semiconducting nanowires (NWs) 3---7 that offer a unique degree of freedom in the design and control of quantum states 8---11 . The most intriguing opportunity offered by these material combinations is the possibility to drive novel excitations and properties that none of the individual device components originally possessed. Recently, this possibility was at the base of the proposal to obtain Majorana---like excitations in semiconducting NWs 11---15 , where pairing correlations can be combined with Rashba spin---orbit coupling 15---18 . Hybrid NWs---SC Josephson junctions are typically obtained by transferring NWs to a Si/SiO2 substrate, on top of which device electrodes are nanofabricated by aligned e---beam lithography. Future advancements in the field and a better understanding of the exotic excitations induced in NW---SC hybrid structures will also depend on the possibility to realize devices having complex architectures, such as systems comprising several NWs connected in a controlled way 19 . Moreover, in these hybrid devices the NW---to---substrate interaction is known to play an important role in terms of induced disorder and by the breaking of inversion symmetry in the electrostatic environment in which the nanostructure is embedded. This is believed to lead to a pinning of the Rashba vector within the plane of the host Si substrate 20 . In this letter we demonstrate a rapid and effective method to realize NW---based suspended Josephson junctions where nanostructure positioning is obtained by dielectrophoresis (DEP) on previously patterned electrodes 21---23 . In our devices, single NWs are aligned on electrode pairs separated by nanogaps approx. , corresponding to a dimension which is over one order of magnitude smaller than the NW length. This is an unusual and challenging DEP configuration and we discuss a novel geometry for achieving a good deposition in this regime. We also show that the properties of the hybrid devices realized using this method are comparable with those of conventional non---suspended devices. We believe that ou...

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Charge transport in InAs nanowire Josephson junctions

Cited by 65 publications

References 47 publications

MBE growth of Al/InAs and Nb/InAs superconducting hybrid nanowire structures

MBE growth of Al/InAs and Nb/InAs superconducting hybrid nanowire structures

Electronic structures of [1 1 1]-oriented free-standing InAs and InP nanowires

Suspended InAs nanowire Josephson junctions assembled via dielectrophoresis

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