Abstract
Formation of self-assembling CdSe islands on ZnSe has been achieved using Migration Enhanced Epitaxy (MEE). Atomic Force Microscopy (AFM) images of uncapped samples show spherical islands with a diameter-to-height ratio of 4:1, which is not yet an unambiguous proof for CdSe quantum-dots. Transmission Electron Microscopy (TEM) images from samples with a ZnSe caplayer show an interrupted Quantum Well (QW) with pronounced thickness fluctuations when the CdSe exceeds its critical thickness. Compared to bulk CdSe, the Photoluminescence (PL) peak is blue-shifted by about 0.5 eV. PL Excitation (PLE) experiments indicate that the interrupted layer consists of CdSe islands embedded in Zn1−xCdxSe with a composition gradient. Temperature dependence of the integrated PL-intensity exhibits thermal quenching with an activation energy of about 100 meV. The red-shift of peak-energy with temperature is considerably larger than the decrease of the bandgap of bulk CdSe.