具有I型能带排列的间接带隙（In，Al）As/AlAs量子点中纵向磁场下激子的光学取向

Optical Orientation of Excitons in a Longitudinal Magnetic Field in Indirect-Band-Gap (In,Al)As/AlAs Quantum Dots with Type-I Band Alignment.

作者信息

Shamirzaev T S, Shumilin A V, Smirnov D S, Kudlacik D, Nekrasov S V, Kusrayev Yu G, Yakovlev D R, Bayer M

机构信息

Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.

Novosibirsk State University, 630090 Novosibirsk, Russia.

出版信息

Nanomaterials (Basel). 2023 Feb 14;13(4):729. doi: 10.3390/nano13040729.

DOI:10.3390/nano13040729

PMID:36839097

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9963670/

Abstract

Exciton recombination and spin dynamics in (In,Al)As/AlAs quantum dots (QDs) with indirect band gap and type-I band alignment were studied. The negligible (less than 0.2 μeV) value of the anisotropic exchange interaction in these QDs prevents the mixing of the excitonic basis states and makes the formation of spin-polarized bright excitons possible under quasi-resonant, circularly polarized excitation. The recombination and spin dynamics of excitons are controlled by the hyperfine interaction between the electron and nuclear spins. A QD blockade by dark excitons was observed in the magnetic field, that eliminates the impact of nuclear spin fluctuations. A kinetic model which accounts for the population dynamics of the bright and dark exciton states as well as for the spin dynamics was developed to quantitatively describe the experimental data.

摘要

研究了具有间接带隙和I型能带排列的(In,Al)As/AlAs量子点（QD）中的激子复合和自旋动力学。这些量子点中各向异性交换相互作用的值可忽略不计（小于0.2 μeV），这阻止了激子基态的混合，并使得在准共振圆偏振激发下形成自旋极化亮激子成为可能。激子的复合和自旋动力学由电子与核自旋之间的超精细相互作用控制。在磁场中观察到暗激子对量子点的阻塞，这消除了核自旋涨落的影响。建立了一个动力学模型，该模型考虑了亮激子态和暗激子态的布居动力学以及自旋动力学，以定量描述实验数据。