Excited-state indirect excitons in GaAs quantum dot molecules
Excited-state indirect excitons in GaAs quantum dot molecules
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DOI：
10.1103/physrevb.96.085408
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发表时间：
2017-08-04
影响因子：
3.7
通讯作者：
Hansen, W.
中科院分区：
文献类型：
--
作者：
Heyn, Ch.;Kuester, A.;Hansen, W.
我们展示了通过填充液滴刻蚀的纳米孔来制备无应变和可广泛调节的GaAs量子点分子(QDM)。高度不对称的QDM的栅极电压依赖的光谱表现出明显的抗交叉，这清楚地表明了与离域分子态的强烈耦合。此外，还观察到与位于不同点的激发态电子和基态空穴的复合有关的间接激子。简单的数值模拟再现了直接跃迁和间接跃迁随电场变化的能量变化，并预测了它们的辐射寿命。激发态间接激子的能见度，即使在强非共振能量失谐的情况下，也表明了声子瓶颈的存在，它将激发电子的驰豫抑制到较低的能级。
We demonstrate the fabrication of strain-free and widely adjustable GaAs quantum-dot molecules (QDMs) by filling of droplet etched nanoholes in AlGaAs. Gate-voltage dependent optical spectra of highly asymmetric QDMs exhibit anticrossings that clearly indicate strong coupling with delocalized molecule states. Furthermore, indirect excitons are observed that are related to recombinations of excited-state electrons and ground-state holes both located in different dots. Simple numerical simulations reproduce the electric-field dependent energy shifts of direct and indirect transitions and predict their radiative lifetimes. The visibility of excited-state indirect excitons even for strong off-resonant energy detuning indicates the presence of a phonon bottleneck which suppresses the relaxation of excited electrons into lower levels.