Confinement of excitons in spherical quantum dots

The ground-state energy of excitons confined in microspherical crystallites with a finite-height potential wall is studied variationally as a function of the particle radius in the so-called strong-confinement regime. Exciton energies for dot radii in the range 5-40 Angstrom are calculated and compared with experimental and theoretical data for CdS, CdSe, PbS and CdTe crystallites. This comparison shows that the effective-mass approximation and spherical confinement geometries are appropriate for all of the particle sizes. Our results also show that the quantum dot cannot be modelled using an infinite-barrier-height potential in the strong-confinement regime.