Selective-Area Superconductor Epitaxy to Ballistic Semiconductor Nanowires

Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grow semiconductor indium antimonide nanowires that are coated with shells of tin of uniform thickness. No interdiffusion is observed at the interface between Sn and InSb. Tunnel junctions are prepared by in-situ shadowing. Despite the lack of lattice matching between Sn and InSb a 15 nm thick shell of tin is found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4T. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.

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“…1A). We expect that junctions defined by wet etching or liftoff would yield similar results (37,38).…”

mentioning

confidence: 90%

Parity-preserving and magnetic field–resilient superconductivity in InSb nanowires with Sn shells

Pendharkar

Zhang

et al. 2021

Science

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“…Using a similar treatment sequence [146], the InSb device shows clear ballistic transport properties. In another report [147], Gill et al deposited an Al shell epitaxially on a selective area of the InSb NW after S-cleaning and low-power argon cleaning. The obtained device showed high interface quality and exhibited a hard superconducting gap and near no-loss transmission of the supercurrent in a single-mode regime.…”

Section: Semiconductor-superconductor Interface Engineeringmentioning

confidence: 99%

Recent advances in III-Sb nanowires: from synthesis to applications

Yip

Shen

2019

Nanotechnology

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The excellent properties of III-V semiconductors make them intriguing candidates for nextgeneration electronics and optoelectronics. Their nanowire (NW) counterparts further provide interesting geometry and a quantum confinement effect which benefits various applications. Among the many members of all the III-V semiconductors, III-antimonide NWs have attracted significant research interest due to their narrow, direct bandgap and high carrier mobility. However, due to the difficulty of NW fabrication, the development of III-antimonide NWs and their corresponding applications are always a step behind the other III-V semiconductors. Until recent years, because of advances in understanding and fabrication techniques, electronic and optoelectronic devices based on III-antimonide NWs with novel performance have been fabricated. In this review, we will focus on the development of the synthesis of III-antimonide NWs using different techniques and strategies for fine-tuning the crystal structure and composition as well as fabricating their corresponding heterostructures. With such development, the recent progress in the applications of III-antimonide NWs in electronics and optoelectronics is also surveyed. All these discussions provide valuable guidelines for the design of III-antimonide NWs for next-generation device utilization.

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“…Since then, significant progress has been made in Majorana experiments [11][12][13][14], enabled by more uniform coupling between the superconductor and semiconductor nanowire. This has been achieved by improved interface engineering: through careful ex situ processing [15][16][17], by depositing the superconductor on the nanowires in situ [18,19], and a combination of in situ and ex situ techniques [20], finally leading to the quantization of the Majorana conductance [13].…”

Section: Introductionmentioning

confidence: 99%

Electric field tunable superconductor-semiconductor coupling in Majorana nanowires

et al. 2018

Self Cite

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We study the effect of external electric fields on superconductor-semiconductor coupling by measuring the electron transport in InSb semiconductor nanowires coupled to an epitaxially grown Al superconductor. We find that the gate voltage induced electric fields can greatly modify the coupling strength, which has consequences for the proximity induced superconducting gap, effective g-factor, and spin-orbit coupling, which all play a key role in understanding Majorana physics. We further show that level repulsion due to spin-orbit coupling in a finite size system can lead to seemingly stable zero bias conductance peaks, which mimic the behavior of Majorana zero modes. Our results improve the understanding of realistic Majorana nanowire systems. gate induced electric fields. Due to the change in coupling, the renormalization of material parameters is altered, as evidenced by a change in the effective g-factor of the hybrid system. Furthermore, the electric field is shown to affect the spin-orbit interaction, revealed by a change in the level repulsion between Andreev states. Our experimental findings are corroborated by numerical simulations. Experimental set-upWe have performed tunneling spectroscopy experiments on four InSb-Al hybrid nanowire devices, labeled A-D, all showing consistent behavior. The nanowire growth procedure is described in [20]. A scanning electron micrograph (SEM) of device A is shown in figure 1(a). Figure 1(b) shows a schematic of this device and the measurement set-up. For clarity, the wrap-around tunnel gate, tunnel gate dielectric and contacts have been removed on one side. A normal-superconductor (NS) junction is formed between the part of the nanowire covered by a thin shell of aluminum (10 nm thick, indicated in green, S), and the Cr /Au contact (yellow, N). The transmission of the junction is controlled by applying a voltage V Tunnel to the tunnel gate (red), galvanically isolated from the nanowire by 35 nm of sputtered SiN x dielectric. The electric field is induced by a global back gate voltage V BG , except in the case of device B, where this role is played by the side gate voltage V SG . Further details on device fabrication and design are included in appendices A and B. To obtain information about the density of states (DOS) in the proximitized nanowire, we measure the differential conductance dI/dV Bias as a function of applied bias voltage V Bias . In the following, we will label this quantity as dI/dV for brevity. A magnetic field is applied along the nanowire direction (x-axis in figures 1(b), (c)). All measurements are performed in a dilution refrigerator with a base temperature of 20 mK. Theoretical modelThe device geometry used in the simulation is shown in figure 1(c). We consider a nanowire oriented along the x-direction, with a hexagonal cross-section in the yz-plane. The hybrid superconductor-nanowire system is described by the Bogoliubov-de Gennes (BdG) Hamiltonian

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Selective-Area Superconductor Epitaxy to Ballistic Semiconductor Nanowires

Cited by 18 publications

References 51 publications

Parity-preserving and magnetic field–resilient superconductivity in InSb nanowires with Sn shells

Parity-preserving and magnetic field–resilient superconductivity in InSb nanowires with Sn shells

Recent advances in III-Sb nanowires: from synthesis to applications

Electric field tunable superconductor-semiconductor coupling in Majorana nanowires

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