DIELECTRIC CONFINEMENT EFFECTS ON THE IMPURITY AND EXCITON BINDING-ENERGIES OF SILICON DOTS COVERED WITH A SILICON DIOXIDE LAYER

The binding energies of hydrogenic impurities and excitons in silicon (Si) dots modelled by a sphere covered with a silicon dioxide (SiO2) l ayer and embedded in various dielectric media, are calculated as a fun ction of the sphere size and the thickness of tile oxide, The strong-c onfinement limit was considered, so that all of the electrostatic inte ractions are treated as first-order perturbations considering the conf ined free-electron state as the unperturbed state. A recently proposed size correction for the dielectric constant of the Si dot is also tak en into account. These calculations demonstrate the importance of the image-charge effect due to dielectric discontinuity In addition, it is shown that the binding energies oi. the impurities and the excitons i nside the silicon dots are greatly affected by alteration of the thick ness of the oxides or the surrounding dielectric media.