Andreev Interference in the Surface Accumulation Layer of Half‐Shell InAsSb/Al Hybrid Nanowires

Abstract

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 half‐shell InAsSb/Al nanowires is 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, exhibit 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 is tunable by a gate potential as expected from electrostatic models.

Effects of Parity and Symmetry on the Aharonov–Bohm Phase of a Quantum Ring

“…With a physical diameter of 80 nm, we note a similar 10 nm difference in radius as that for the type B case, which points to a substantial weight of the wave function rather close to the NW surface. This direct correlation of ring and nanowire diameters, and a D AB that seems to be independent of electron number within the range of Figure b, supports the presence of a surface electron accumulation layer …”

“…Sample A has a QD of pure InAs, whereas B has an additional thin outer shell of InAsSb. Surface-related band bending in InAs and InAsSb is key to the formation of the ring-like states that we observe. The interior of the QD has no filled states due to the strong confinement, while electrons can still accumulate near the surface .…”

“…In this work, we have experimentally and theoretically examined the AB effect in structures similar to those in ref , where phase-coherent quantum rings form near the surface of nanowires with epitaxially defined QDs. Using transport measurements, we find AB flux periodicities corresponding to rings that have an approximately 10 nm smaller radius than the nanowire, consistent with a surface accumulation layer of electrons . We realize one-dimensional rings with different symmetries and observe a huge orbital contribution to the electron g -factor for high symmetry cases.…”

Epitaxial growth of crystal phase quantum dots in III–V semiconductor nanowires

“…A pure ZB-InAs QD for sample A, and the same structure together with a thin InAsSb shell for sample B. Surface band bending in the InAs and in the thin InAsSb shell is crucial for the appearance of the ring-like QD in InAs 184 and InAsSb 185 . The strong confinement inside the QD produced the absence of filled states, while electrons can accumulate close to the surface 77 .…”

“…Surface band bending in the InAs and in the thin InAsSb shell is crucial for the appearance of the ring-like QD in InAs 183 and InAsSb. 184 The strong confinement inside the QD produced the absence of filled states, while electrons can accumulate close to the surface. 76 However, the resulting ring-like states around the NW surface are sensitive to perturbations, resulting in localized electron states.…”