Cathodoluminescence and TEM studies of MBE-grown CdSe submonolayers in ZnSe matrix, cladded by ZnSSe, ZnSe and ZnMgSe

Abstract

We have studied MBE-grown CdSe submonolayers (SMLs) using cathodoluminescence (CL) and transmission electron microscopy (TEM). The CdSe SMLs were embedded into ZnSe matrix layer and made to undergo different lattice strains from thick ZnSSe, ZnSe and ZnMgSe cladding layers. It was revealed that the CdSe SML emission line has different energy position and FWHM for the structures with variable cladding layers. This characteristic is attributed to the effect of strain in the ZnSe matrix layer and its surface roughness on the CdSe distribution along the surface. At the deposition of the CdSe SMLs on unstrained flat surface of ZnSe, the homogeneous quantum well (QW)-like CdZnSe alloy layer is formed. Using the strained roughness surface increases fluctuations in the Cd distribution along the surface. While, assuming the compressive ZnSe matrix (ZnSSe cladding layers), the CL line has to be broadening for the CdSe cluster organization only, in the case of structures with ZnMgSe cladding layers, low-energy offset is observed. This is due to the creation of the CdSe ML islands with relatively large lateral size.