Parameters of bound multiexciton complexes in direct polar semiconductors

Using a generalized density-functional method, which takes electron-phonon interaction into account, the ground state energies of donor BMEC's D0X/sub m/(m = 1, ..., 20) are calculated for the polar semiconductors ZnS, CdS, and CdSe. The highest stability is obtained for complexes possessing filled electron shells (m = 1, 7, 19), whereas gaps of instability are located between these complexes. The spectral locations of luminescence lines connected with the radiative decay of BMEC's are predicted and found to be concentrated between the luminescence lines of the bound exciton and the free exciton. Furthermore, analytic approximate expressions for the electron and hole densities are obtained and their shapes are extensively discussed. (author)