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/InGaAs/InP quantum dots exhibit favorable spin properties for potential implementation in quantum information applications.