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Radial etching of strongly confined crystal-phase defined quantum dots

Aspegren, Markus LU ; Mkolongo, Chris LU ; Lehmann, Sebastian LU ; Dick, Kimberly LU ; Burke, Adam LU orcid and Thelander, Claes LU (2026) In Nanotechnology 37(11).
Abstract

We realize strongly confined quantum dots (QDs) in InAs nanowires (NWs) by combining epitaxial crystal-phase control with chemical wet etching. A strong axial confinement is first introduced by growing closely spaced wurtzite (WZ) tunnel barriers in NWs to enclose a zinc blende (ZB) QD. The NW cross-section is then reduced by isotropic etching to obtain very small QDs, with a maximum observed charging energy > 30meV. Using low-temperature electrical characterization and finite-element method simulations, we study how charging energies and the onset of electron filling scale with QD diameter. For extremely small diameters, we identify a regime where stray capacitances become non-negligible, limiting further increase in charging energy... (More)

We realize strongly confined quantum dots (QDs) in InAs nanowires (NWs) by combining epitaxial crystal-phase control with chemical wet etching. A strong axial confinement is first introduced by growing closely spaced wurtzite (WZ) tunnel barriers in NWs to enclose a zinc blende (ZB) QD. The NW cross-section is then reduced by isotropic etching to obtain very small QDs, with a maximum observed charging energy > 30meV. Using low-temperature electrical characterization and finite-element method simulations, we study how charging energies and the onset of electron filling scale with QD diameter. For extremely small diameters, we identify a regime where stray capacitances become non-negligible, limiting further increase in charging energy by diameter reduction alone. This approach to increasing confinement is particularly relevant for understanding the strong spin–orbit interaction observed in crystal-phase QDs, possibly linked to polarization charges at the WZ/ZB interfaces. Small diameter QDs allow considerably weaker interfering electric fields when studied, but the QDs cannot be realized with epitaxial growth alone due to a loss of crystal phase control.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
crystal-phase engineering, enhanced charging energy, enhanced confinement, finite-element simulations, InAs nanowire, quantum dot, wet etching
in
Nanotechnology
volume
37
issue
11
article number
115001
pages
8 pages
publisher
IOP Publishing
external identifiers
  • pmid:41780075
  • scopus:105033862810
ISSN
0957-4484
DOI
10.1088/1361-6528/ae4d50
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2026 The Author(s). Published by IOP Publishing Ltd.
id
e8b49db2-da63-40b0-be60-f32a41be6118
date added to LUP
2026-06-10 10:16:11
date last changed
2026-08-20 22:07:04
@article{e8b49db2-da63-40b0-be60-f32a41be6118,
  abstract     = {{<p>We realize strongly confined quantum dots (QDs) in InAs nanowires (NWs) by combining epitaxial crystal-phase control with chemical wet etching. A strong axial confinement is first introduced by growing closely spaced wurtzite (WZ) tunnel barriers in NWs to enclose a zinc blende (ZB) QD. The NW cross-section is then reduced by isotropic etching to obtain very small QDs, with a maximum observed charging energy &gt; 30meV. Using low-temperature electrical characterization and finite-element method simulations, we study how charging energies and the onset of electron filling scale with QD diameter. For extremely small diameters, we identify a regime where stray capacitances become non-negligible, limiting further increase in charging energy by diameter reduction alone. This approach to increasing confinement is particularly relevant for understanding the strong spin–orbit interaction observed in crystal-phase QDs, possibly linked to polarization charges at the WZ/ZB interfaces. Small diameter QDs allow considerably weaker interfering electric fields when studied, but the QDs cannot be realized with epitaxial growth alone due to a loss of crystal phase control.</p>}},
  author       = {{Aspegren, Markus and Mkolongo, Chris and Lehmann, Sebastian and Dick, Kimberly and Burke, Adam and Thelander, Claes}},
  issn         = {{0957-4484}},
  keywords     = {{crystal-phase engineering; enhanced charging energy; enhanced confinement; finite-element simulations; InAs nanowire; quantum dot; wet etching}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{11}},
  publisher    = {{IOP Publishing}},
  series       = {{Nanotechnology}},
  title        = {{Radial etching of strongly confined crystal-phase defined quantum dots}},
  url          = {{http://dx.doi.org/10.1088/1361-6528/ae4d50}},
  doi          = {{10.1088/1361-6528/ae4d50}},
  volume       = {{37}},
  year         = {{2026}},
}