CdSe/ZnSe Quantum Dot Structures: Structural and Optical Investigations

Using migration enhanced epitaxy the self-organized formation of CdSe islands on ZnSe in open and overgrown structures has been studied by transmission electron microscopy, high-resolution X-ray diffraction, atomic force microscopy, photoluminescence and excitation spectroscopy. The transition from homogeneous CdSe quantum wells with flat interfaces to fluctuating CdSe films could be observed when exceeding the critical thickness. These interrupted layers contain CdSe quantum dots embedded in Cd_1—xZn_xSe with a concentration gradient. Islands observed on open structures are unstable in time. Their chemical nature is still unclear due to the fact that similar features are obtained on pure ZnSe. First results on other highly lattice mismatched II–VI systems like CdTe/ZnSe and ZnTe/ZnSe will be presented.