Spatial separation effect on the energies of uncorrelated and correlated electron-hole pair in CdSe/ZnS and InAs/InP core/shell spherical quantum dots

The control of charge carriers states in coated semiconductors quantum dots constitute a challenge to achieve a new range of tunable optoelectronic devices. The purpose of this work is to investigate the ground state energies and the behaviors of correlated and non correlated pair of electron (e) and hole (h) in CdSe/ZnSe and InAs/InP type I core/shell spherical quantum dots taking into account the discontinuities of the dielectric constants and effective masses. Analytical study of the uncorrelated e and h states allows to evaluate the critical values of the core size corresponding to the escape of the electron and hole from the core to the shell material. Then, the confined e and h wave functions and their fundamental energies are determined according to their localization in the core/shell structure. Knowing that the electron-hole interaction i.e “excitonic effect” turns out to be crucial for a comprehension of the optical spectra, we extend our concept to the investigation of the electron-hole correlations by a variational method.