发表机构
Ioffe Institute（约费研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出半导体纳米片单体和ensemble中激子光学对准与取向理论，考虑亮暗激子发射及对称性，示例计算CdSe/CdS核壳结构，并展示参数波动对偏振退相的影响。
AI 中文摘要
我们提出了在单个半导体纳米片（NPL）和NPL ensemble 中激子光学对准和光学取向效应的理论。该理论模型考虑了在强电子-空穴交换相互作用以及NPL边缘相对于线性偏振轴的面内取向各向同性分布情况下，来自亮激子和暗激子态的发射。考虑了在偏振共振激发亮激子时线性光学响应区域的条件，并给出了在法拉第磁场中正常入射下低温情况下的稳态和时间依赖的偏振光致发光表达式。所获得的光学响应的对称性对应于单个NPL的$C_{2}$点群和NPL ensemble 的$C_{\infty}$点群。考虑了允许观察暗激子光学对准的亮-暗激子耦合机制。对于接近CdSe/CdS核/壳NPL的参数，给出了效应的示例计算。演示了ensemble 中激子参数波动对横向有效磁场中偏振退相的影响。
英文摘要
We present the theory of exciton optical alignment and optical orientation effects in a single semiconductor nanoplatelet (NPL) and in an ensemble of NPLs. The theoretical model is developed to take into account the emission from both bright and dark exciton states in the case of strong electron-hole exchange interaction and an isotropic distribution of in-plane orientations of the NPLs' edges with respect to the linear polarization axis. The conditions for the linear optical response regime on the polarized resonant excitation of the bright exciton are considered, and the steady-state and time-dependent expressions for polarized photoluminescence are presented for the low temperature case in the Faraday magnetic field at normal incidence. The symmetry of the obtained optical response corresponds to the $C_{2}$ point group for the single NPL and the $C_{\infty}$ point group for the NPL ensemble. The bright-to-dark exciton coupling mechanism allowing one to observe the optical alignment of the dark exciton is considered. The example calculations of the effects are presented for the parameters close to those of CdSe/CdS core/shell NPLs. The effect of the fluctuations in the exciton parameters in the ensemble on the polarization dephasing in the transverse effective magnetic field is demonstrated.
