Formation processes of CdTe quantum dots on ZnTe substrates studied by reflection high-energy electron diffraction and photoluminescence

Formation processes of self-organized CdTe quantum dots (QDs) grown on ZnTe (001) substrates by molecular beam epitaxy were studied. In situ reflection high-energy electron diffraction (RHEED) was used to study the initial growth processes and strain relaxation behaviors of CdTe QDs. The growth process of CdTe layer at the initial stage can be divided into three stages: (1) stable two-dimensional (2D) growth, (2) metastable 2D growth just before the QD formation, and (3) QD formation. It was found that the critical thickness for the 2D-3D transition is about 5.5 monolayers (ML) at the growth rate of 0.12 ML/s. The results of photoluminescence (PL) and μ-PL agree with the RHEED observations. In addition, by investigating the dependence of PL peak energy on the growth temperature, we found that interdiffusion between the cations (Cd and Zn) is activated at a higher growth temperature.