CDS QUANTUM DOTS IN THE WEAK CONFINEMENT

By means of linear and nonlinear spectroscopy, the energy states and linewidths were investigated for CdS quantum dots under weak confinement grown in the coalescent or normal growth process. The homogeneous line broadening measured by differential absorption spectroscopy and non-degenerate four-wave mixing is strongly influenced by the interface properties and is considerably larger than reported for bulk CdS. This difference has been attributed to a dephasing process introduced by interface polarizations. The direct electron-hole pair recombination is characterized by a sharp luminescence peak 20 meV below the absorption band. The Huang-Rhys parameters have been estimated from both the luminescent Stokes shift and the linewidth, and good agreement has been achieved.