3 research outputs found
Quantized Conductance in an InSb Nanowire
Ballistic one-dimensional transport in semiconductor
nanowires
plays a central role in creating topological and helical states. The
hallmark of such one-dimensional transport is conductance quantization.
Here we show conductance quantization in InSb nanowires at nonzero
magnetic fields. Conductance plateaus are studied as a function of
source-drain bias and magnetic field, enabling extraction of the Landé <i>g</i> factor and the subband spacing
First-Principles Assessment of CdTe as a Tunnel Barrier at the α‑Sn/InSb Interface
Majorana zero modes, with prospective applications in
topological
quantum computing, are expected to arise in superconductor/semiconductor
interfaces, such as β-Sn and InSb. However, proximity to the
superconductor may also adversely affect the semiconductor’s
local properties. A tunnel barrier inserted at the interface could
resolve this issue. We assess the wide band gap semiconductor, CdTe,
as a candidate material to mediate the coupling at the lattice-matched
interface between α-Sn and InSb. To this end, we use density
functional theory (DFT) with Hubbard U corrections, whose values are
machine-learned via Bayesian optimization (BO) [npj Computational Materials 2020, 6, 180]. The results of DFT+U(BO) are validated against angle resolved
photoemission spectroscopy (ARPES) experiments for α-Sn and
CdTe. For CdTe, the z-unfolding method [Advanced Quantum Technologies 2022, 5, 2100033] is used to resolve the contributions of different kz values to the ARPES. We then study
the band offsets and the penetration depth of metal-induced gap states
(MIGS) in bilayer interfaces of InSb/α-Sn, InSb/CdTe, and CdTe/α-Sn,
as well as in trilayer interfaces of InSb/CdTe/α-Sn with increasing
thickness of CdTe. We find that 16 atomic layers (3.5 nm) of CdTe
can serve as a tunnel barrier, effectively shielding the InSb from
MIGS from the α-Sn. This may guide the choice of dimensions
of the CdTe barrier to mediate the coupling in semiconductor–superconductor
devices in future Majorana zero modes experiments
From InSb Nanowires to Nanocubes: Looking for the Sweet Spot
High aspect ratios are highly desired to fully exploit
the one-dimensional properties of indium antimonide nanowires. Here
we systematically investigate the growth mechanisms and find parameters
leading to long and thin nanowires. Variation of the V/III ratio and
the nanowire density are found to have the same influence on the “local”
growth conditions and can control the InSb shape from thin nanowires
to nanocubes. We propose that the V/III ratio controls the droplet
composition and the radial growth rate and these parameters determine
the nanowire shape. A sweet spot is found for nanowire interdistances
around 500 nm leading to aspect ratios up to 35. High electron mobilities
up to 3.5 × 10<sup>4</sup> cm<sup>2</sup> V<sup>–1 </sup>s<sup>–1</sup> enable the realization of complex spintronic
and topological devices