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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\n                    <jats:inline-formula>\n                      <jats:tex-math>\n                        \n                      <\/jats:tex-math>\n                      <mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" overflow=\"scroll\">\n                        <mml:mrow>\n                          <mml:mo>&gt;<\/mml:mo>\n                          <mml:mn>30<\/mml:mn>\n                        <\/mml:mrow>\n                      <\/mml:math>\n                    <\/jats:inline-formula>\n                    \u2009meV. 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\u2013orbit 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.\n                  <\/jats:p>","DOI":"10.1088\/1361-6528\/ae4d50","type":"journal-article","created":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T22:48:05Z","timestamp":1772664485000},"page":"115001","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Radial etching of strongly confined crystal-phase defined quantum dots"],"prefix":"10.1088","volume":"37","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4846-7796","authenticated-orcid":true,"given":"Markus","family":"Aspegren","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-3254-3674","authenticated-orcid":true,"given":"Chris","family":"Mkolongo","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sebastian","family":"Lehmann","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kimberly","family":"Dick","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9345-2812","authenticated-orcid":true,"given":"Adam","family":"Burke","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Claes","family":"Thelander","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"266","published-online":{"date-parts":[[2026,3,16]]},"reference":[{"key":"nanoae4d50bib1","doi-asserted-by":"publisher","first-page":"1217","DOI":"10.1103\/RevModPhys.79.1217","type":"journal-article","article-title":"Spins in few-electron quantum dots","volume":"79","author":"Hanson","year":"2007","journal-title":"Rev. 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