CONFINEMENT OF EXCITONS IN QUANTUM DOTS

A theoretical study of exciton confinement in small CdS and ZnS quantum dots is reported. In our calculational scheme the hole is described by an effective bond-orbital model that accounts for the valence-band degeneracy in bulk semiconductors. The electron is described with a single-band effective-mass approximation. The confining quantum-dot potentials for the hole and electron are modeled as spherically symmetric potential wells with finite barrier heights. The electron-hole Coulomb attraction is included and exciton energies are obtained variationally in an iterative Hartree scheme. Exciton energies for dot diameters in the range 10-80 angstrom are calculated and compared with experimental data and other theoretical results.