Comparative study of molecular beam and migration-enhanced epitaxy of ZnCdSe quantum wells: influence on interface and composition fluctuations

Optical and structural properties of ZnCdSe quantum wells (QWs) grown by ei ther migration-enhanced epitaxy (MEE) or molecular beam epitaxy (MBE) have been compared. Firstly the QWs are grown by depositing Zn and Cd at the sam e time during MEE. These samples exhibit significantly lower Cd concentrati ons than samples grown by MBE with similar Cd fluxes. Compared to MBE grown samples with similar low Cd concentrations neither photoluminescence (PL) nor high-resolution transmission electron microscopy (HRTEM) reveal signifi cant differences in the optical and structural properties, respectively. Se condly the QWs are grown as a digital alloy by depositing CdSe and ZnSe by turns. In this case typical PL spectra show line widths as narrow as 16 meV which means a reduction of about 10 meV compared to typical values from MB E grown samples. By means of HRTEM this could be correlated to improved int erfaces and a better composition homogeneity. (C) 2000 Elsevier Science B.V . All rights reserved.