Influence of interface growth steps on the anisotropy of excitonic emission in ZnCdSe/ZnSe quantum wells

Spectra of excitonic luminescence of single-quantum-well ZnCdSe/ZnSe heterostructures at T = 8 K are investigated. Two types of linear-polarization anisotropy of the excitonic emission are revealed. The first type of anisotropy corresponds to the luminescence polarization along the [011] axis and is related to the emission from the lower level of the doublet state of heavy-hole excitons localized in the islands elongated in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$[0\overline 1 1]$$ \end{document} direction. The second type of anisotropy is related to the generation of free excitons with wave vectors exceeding that of light. Such a process is made possible by the elastic scattering of light at anisotropic interface-roughness structure originating from the growth steps. In this case, the emission is polarized along the [0-11] axis and the anisotropy is caused by deformation effects that lead to the perturbation of the hole states in the vicinity of the growth steps. The deformation appears due to a mismatch between the lattice constants of the barrier and the well materials.