ABSTRACT
CdSe-based islands observed as light circle-shaped objects with a factor of two lower density (5x108cm-2) and larger lateral sizes (10-15 nm), in line with a cross-section TEM observation. However the PL spectrum of structure C demonstrates much smaller red shift of the peak energy and reduced intensity, perhaps due to defect occurrence, as well as line broadening up to 64 meV. Such smaller PL peak energy shift at larger island sizes evidences that the significant Cd re-evaporation takes place during growth interruption at the Cd-terminated surface in addition to faster Cd surface redistribution. Finally, structure D, demonstrating the effect of Ts rising on the structure A morphology shows more homogeneous Cd redistribution along the CdSe sheet, keeping its average broadening unchanged. The thinner TEM sample regions reveal high-density (-10 11 cm-2) small-scale QD islands with the lateral size ranging between 5 and 10 nm, which is reflected in dramatic broadening of the PL band width. Pronounced blue shift of the PL band indicates both an enhancement of the quantum confinement in the small QDs and, perhaps, an onset ofCd re-evaporation at high enough Ts.
