Interplay of surface charges and excitons localized in CdSe/ZnSe quantum dots

Spectral diffusion is an effect often observed in epitaxially grown II–VI quantum dots. It is shown that in such structures spectral diffusion is caused by electric fields generated from charges on the sample surface. The interaction mechanism is a linear quantum-confined Stark effect revealing an electric dipole moment of the zero-dimensional multi-exciton states in the quantum dot. The dipole length of all the observed multi-exciton states is almost the same suggesting a negligible correlation of the electron and hole wave functions caused by a strong vertical confinement.