Shadow-wall lithography of ballistic superconductor-semiconductor quantum devices

Heedt, Sebastian; Quintero-Pérez, Marina; Borsoi, Francesco; Fursina, Alexandra; van Loo, Nick; Mazur, Grzegorz P.; Nowak, Michał P.; Ammerlaan, Mark; Li, Kongyi; Korneychuk, Svetlana; Shen, Jie; van de Poll, May An Y.; Badawy, Ghada; Gazibegovic, Sasa; van Hoogdalem, Kevin; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.

doi:10.48550/arxiv.2007.14383

Cited by 6 publications

(14 citation statements)

References 49 publications

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“…Figure 1b shows the differential resistance dV /dI of JJ Devices 1 and 3 as a function of the perpendicular out-of-plane magnetic field B z sweeping I from negative to positive. A zero-resistance superconducting region is observed at low currents and the switching current where the device switches to a finite resistance state decreases monotonously with B z and at B c z ∼ 150 mT superconductivity is completely suppressed consistent with previous measurements of epitaxial hybrid nanowires in a perpendicular field [17,21]. A strikingly different behavior is observed in the corresponding measurement performed with the field B applied parallel to the NW (Fig.…”

Section: Resultssupporting

confidence: 88%

“…The extracted gap is ∆ = 225 µeV consistent with the expected gap of the Al hybrids [17]. In addition to the MAR features, spectroscopic measurements also probe sub-gap states in the leads [21] and Fig. 3c shows a measurement of the spectrum as a function of B for a fixed V BG = −30 V. A rich spectrum emerges at finite B which is originating from the 2∆ peak and is following a pattern modulating similar to the switching current in Figs.…”

Section: (A) (Red Trace)supporting

confidence: 73%

“…High-mobility semiconductor NWs can now be grown into complex geometries [15,16] with a negligible amount of crystal defects, and the development of insitu growth of epitaxial semiconductor/superconductor hybrids [13] enables reproducible, uniform contacting and improved character of induced superconductivity [17]. Finally, in-situ shadow patterning methods have been developed to reduce post growth processing [16,[18][19][20][21] and thus significantly reduce random scattering from surface adsorbents, and improve reproducibility and electrostatic stability. With minimal disorder and extrinsic random scattering, intrinsic properties such as the non-uniform carrier distribution can be dominating.…”

mentioning

confidence: 99%

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Andreev interference in the surface accumulation layer of half-shell InAsSb/Al hybrid nanowires

Stampfer¹,

Carrad²,

Olsteins³

et al. 2021

Preprint

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Understanding the spatial distribution of charge carriers in III-V nanowires proximity coupled to superconductors is important for the design and interpretation of experiments based on hybrid quantum devices. In this letter, the gate-dependent surface accumulation layer of InAsSb/Al nanowires was studied by means of Andreev interference in a parallel magnetic field. Both uniform hybrid nanowires and devices featuring a short Josephson junction fabricated by shadow lithography, exhibited periodic modulation of the switching current. The period corresponds to a flux quantum through the nanowire diameter and is consistent with Andreev bound states occupying a cylindrical surface accumulation layer. The spatial distribution was tunable by a gate potential as expected from electrostatic models.

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Section: Resultssupporting

confidence: 88%

Section: (A) (Red Trace)supporting

confidence: 73%

mentioning

confidence: 99%

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Andreev interference in the surface accumulation layer of half-shell InAsSb/Al hybrid nanowires

Stampfer¹,

Carrad²,

Olsteins³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…In most cases, to identify non-Majorana states it is sufficient to analyze two-terminal measurements on just one nanowire in a self-consistent fashion. However, positive identification of MZM will likely require threeterminal measurements on both nanowire ends [25,[27][28][29][30][31]. More generally, the three-terminal technique is a powerful method of studying the localization of any wavefunctions, which is what we do in this work.…”

mentioning

confidence: 92%

Delocalized states in three-terminal superconductor-semiconductor nanowire devices

Yu¹,

Woods²,

Chen³

et al. 2021

Preprint

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We fabricate three-terminal hybrid devices with a nanowire segment proximitized by a superconductor, and with two tunnel probe contacts on either side of that segment. We perform simultaneous tunneling measurements on both sides. We identify some states as delocalized above-gap states observed on both ends, and some states as localized near one of the tunnel barriers. Delocalized states can be traced from zero to finite magnetic fields beyond 0.5 T. In the parameter regime of delocalized states, we search for correlated subgap resonances required by the Majorana zero mode hypothesis. While both sides exhibit ubiquitous low-energy features at high fields, no correlation is inferred. Simulations using a one-dimensional effective model suggest that delocalized states may belong to lower one-dimensional subbands, while the localized states originate from higher subbands. To avoid localization in higher subbands, disorder may need to be further reduced to realize Majorana zero modes.

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“…[11][12][13][14][15][16] Shadow deposition of superconductors has furthermore successfully been used, to avoid etching damage and the need of developing etching procedures. [17][18][19][20] The downside of these out-of-plane synthesized wires is the limited geometric flexibility in creating networks.…”

mentioning

confidence: 99%

Universal Platform for Scalable Semiconductor-Superconductor Nanowire Networks

Jung¹,

Veld²,

Benoist³

et al. 2021

Preprint

Self Cite

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Semiconductor-superconductor hybrids are commonly used in research on topological quantum computation. Traditionally, top-down approaches involving dry or wet etching are used to define the device geometry. These often aggressive processes risk causing damage to material surfaces, giving rise to scattering sites particularly problematic for quantum applications. Here, we propose a method that maintains the flexibility and scalability of selective area grown nanowire networks while omitting the necessity of etching to create hybrid segments. Instead, it takes advantage of directional growth methods and uses bottom-up grown InP structures as shadowing objects to obtain selective metal deposition. The ability to lithographically define the position and area of these objects, and to grow a predefined height, ensures precise control of the shadowed region. We demonstrate the approach by growing InSb nanowire networks with well-defined Al and Pb islands. Cross-section cuts of the nanowires reveal a sharp, oxide-free interface between semiconductor and superconductor. By growing InP structures on both sides of in-plane nanowires, a combination of Pt and Pb can independently be shadow deposited, enabling a scalable and reproducible in-situ device fabrication. The semiconductor-superconductor nanostructures resulting from this approach are at the forefront of material development for Majorana based experiments.

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Shadow-wall lithography of ballistic superconductor-semiconductor quantum devices

Cited by 6 publications

References 49 publications

Andreev interference in the surface accumulation layer of half-shell InAsSb/Al hybrid nanowires

Andreev interference in the surface accumulation layer of half-shell InAsSb/Al hybrid nanowires

Delocalized states in three-terminal superconductor-semiconductor nanowire devices

Universal Platform for Scalable Semiconductor-Superconductor Nanowire Networks

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