Optical properties of CdS quantum dots: The key role of the spin-orbit and coulomb interactions

We study theoretically and experimentally the effects of the Coulomb and the spin-orbit coupling on the electronic structure of small quantum dots. A tight-binding calculation with restricted configuration interaction is developed in a typical case: very small cubic quantum dots for which the electron-hole exchange interaction is of the order of magnitude of the spin-orbit interaction. Experimentally, resonant photoluminescence and photoluminescence excitation are used to obtain information on a single size of CdS quantum dot obtained by a chemical growth method.