Effect of anisotropy of band structure on optical gain in spherical quantum dots based on PbS and PbSe

Results of an experimental and theoretical study of the optical absorption spectra of spherical quantum dots based on PbS and PbSe are presented. A ri gorous theoretical analysis of the energy spectra and optical transitions i s performed within the framework of the four-band k.p approximation with fu ll account of the effect of anisotropy of the band structure. It is shown t hat strong anisotropy of the band structure of PbS and PbSe leads to the ap pearance of optical transitions that are forbidden in the isotropic approxi mation. These transitions were detected in the optical absorption spectra o f the investigated quantum dots. (C) 1999 American Institute of Physics. [S 1063-7826(99)01112-6].