Investigation of lateral exciton transfer of coexistent quantum dot systems

The optical characterization of the ZnCdSe/ZnSe quantum dot (QDs) system is studied by photoluminescence (PL) spectrum measured at temperatures from 22 to 300 K. The distinct quenching rates of spectral integrated intensity demonstrate that there are divergent lateral exciton transfer modes between two types of coexistent QDs with different sizes and densities. The smaller and denser QD assemblies are advantageous to trigger lateral migration of thermally activated excitons due to their shallower localization and more coupling channels. However, the carrier repopulation-induced redistribution of excitonic emission energy is contrarily observed in the deepest localized case. The extra redshift of transition energy with increasing temperature is attributed to the incompletely three-dimensional excitonic confinement induced by the morphological features. In contrast with scanning probe techniques, using PL as spectral probe is a nondestructive way to explore inner morphology of capped multiple quantum structure.