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 [011] 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 (1) over bar1] 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.