Spin properties in droplet epitaxy grown telecom quantum dots

We investigate the spin properties of InAs/InGaAs/InP quantum dots grown by metalorganic vapor-phase epitaxy (MOVPE) deposition using droplet epitaxy, which emits in the telecom C band. Using pump-probe Faraday ellipticity measurements, we determine electron and hole <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>g</a:mi></a:math> factors of <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mrow><b:mo>|</b:mo></b:mrow><b:msub><b:mi>g</b:mi><b:mi>e</b:mi></b:msub><b:mrow><b:mo>|</b:mo><b:mo>=</b:mo><b:mn>0.93</b:mn></b:mrow></b:mrow></b:math> and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mrow><c:mo>|</c:mo></c:mrow><c:msub><c:mi>g</c:mi><c:mi>h</c:mi></c:msub><c:mrow><c:mo>|</c:mo><c:mo>=</c:mo><c:mn>0.47</c:mn></c:mrow></c:mrow></c:math>, with the electron <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mi>g</d:mi></d:math> factor being nearly twice as low as typical molecular beam epitaxy Stranski-Krastanov (SK) grown samples. Most significantly, we measure a longitudinal spin relaxation time <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mrow><e:msub><e:mi>T</e:mi><e:mn>1</e:mn></e:msub><e:mo>=</e:mo><e:mn>3.0</e:mn><e:mspace width="4pt"/><e:mrow><e:mi>µ</e:mi><e:mi mathvariant="normal">s</e:mi></e:mrow></e:mrow></e:math>, representing an order of magnitude improvement over comparable MBE SK grown samples. Despite significant electron <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mi>g</h:mi></h:math>-factor anisotropy, we observed that it is reduced relative to similar material composition samples grown with MBE or MOVPE SK methods. We attribute this <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:mi>g</i:mi></i:math>-factor anisotropy and spin lifetime improvements to the enhanced structural symmetry achieved via MOVPE droplet epitaxy, which mitigates the inherent structural asymmetry in strain-driven growth approaches for InAs/InP quantum dots. These results demonstrate that MOVPE droplet epitaxy-grown InAs/InGaAcompresss/InP quantum dots exhibit favorable spin properties for potential implementation in quantum information applications.