Droplet epitaxy symmetric InAs/InP quantum dots for quantum emission in the third telecom window: morphology, optical and electronic properties
Droplet epitaxy symmetric InAs/InP quantum dots for quantum emission in the third telecom window: morphology, optical and electronic properties
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DOI：
10.1515/nanoph-2021-0482
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发表时间：
2022-01-28
期刊：
影响因子：
7.5
通讯作者：
Semenova, Elizaveta
中科院分区：
文献类型：
--
作者：
Holewa, Pawel;Kadkhodazadeh, Shima;Semenova, Elizaveta
快速发展的量子通信技术需要能够在第三电信窗口产生单光子和纠缠光子对的确定性量子发射器，以便与现有的光纤网络和片上硅光子处理器兼容。InAs/InP量子点（QD）是用于此目的的主要候选者之一，这是由于它们在所需光谱范围内的高发射效率。然而，制造通用的InAs/InP QD基量子发射器是具有挑战性的，特别是因为这些QD通常在生长平面中具有不对称的轮廓，导致显著的亮激子精细结构分裂（FSS）。这阻碍了纠缠光子对的产生，从而损害了InAs/InP量子点的多功能性。我们通过在（001）取向的InP衬底上实现低表面密度（2.8 x 10（8）cm（-2））InAs x P1-x QD（x =（80 +/- 15）%）的液滴外延（DE）合成来克服这个问题。所得到的量子点位于蚀刻坑中，具有凹基底，并且最重要的是，具有对称的面内轮廓。我们提供了一个分析模型来解释坑的形成和QD基地形状修改的动力学。我们对量子点电子态的理论计算揭示了量子点中的中性和带电激子以及双激子的性质，这与单个量子点的光学研究结果一致。量子点系综的光学响应表明，FSS可能确实可以忽略不计，反映在线性偏振消失的程度。然而，从蚀刻梅萨收集的单量子点光谱显示出（50 +/- 5）μ eV的适度FSS，我们链接到在生长后处理过程中的量子点环境中的破坏性变化。最后，我们表明，所研究的DE量子点提供了一个接近理想的单光子发射纯度为（92.5 +/- 7.5）%，在第三电信窗口。
The rapidly developing quantum communication technology requires deterministic quantum emitters that can generate single photons and entangled photon pairs in the third telecom window, in order to be compatible with existing optical fiber networks and on-chip silicon photonic processors. InAs/InP quantum dots (QDs) are among the leading candidates for this purpose, due to their high emission efficiency in the required spectral range. However, fabricating versatile InAs/InP QD-based quantum emitters is challenging, especially as these QDs typically have asymmetric profiles in the growth plane, resulting in a substantial bright-exciton fine structure splitting (FSS). This hinders the generation of entangled photon pairs and thus, compromises the versatility of InAs/InP QDs. We overcome this by implementing droplet epitaxy (DE) synthesis of low surface density (2.8 x 10(8) cm(-2)) InAs x P1-x QDs with x = (80 +/- 15)% on an (001)-oriented InP substrate. The resulting QDs are located in etched pits, have concave bases, and most importantly, have symmetric in-plane profiles. We provide an analytical model to explain the kinetics of pit formation and QD base shape modification. Our theoretical calculations of electronic states reveal the properties of neutral and charged excitons and biexcitons confined in such QDs, which agree with the optical investigations of individual QDs. The optical response of QDs' ensemble suggests that FSS may indeed be negligible, as reflected in the vanishing degree of linear polarization. However, single QD spectrum gathered from an etched mesa shows moderate FSS of (50 +/- 5) mu eV that we link to destructive changes made in the QD environment during the post-growth processing. Finally, we show that the studied DE QDs provide a close-to-ideal single-photon emission purity of (92.5 +/- 7.5)% in the third telecom window.