Excitons in Indirect Electroabsorption

Electroreflectance: A Status Report

“…As in the case of the absorption coefficient in the absence of electric fields, the more accurate calculations are found to be in gratifying quantitative agreement with experiment for direct transitions [28, 30, 311, suggesting that the Coulomb interaction is the most important of the remaining refinements t o the theory. The fact that good agreement was also found by Lao et al for electroabsorption a t the anisotropic indirect edge of Si indicates that anisotropy effects are secondary [30]. These calculations all show the strong influence of the n = 1 exciton bound state in the ER lineshapes, and the modifications of the one-electron square-root singularity to that of the step function of the Coulomb continuum.…”

“…The exact lineshape solution including both Coulomb and electric-field effects can be obtained for isotropic critical points by numerical methods in the effective mass approximation, where the relative motion part of the pair Hamiltonian is separable in parabolic coordinates. The calculations of Ralph 1271 and Blossey [29] and particularly the extensive results of Dow and co-workers [28,30,311 have given considerable insight into the influence of Coulomb interactions on E R spectra in general, since it is expected that the qualitative effects of bound states and threshold response enhancement should be retained to some degree even if the anisotropy is substantial. This is supported by calculations of the effect of the Coulomb interaction on the density of states in the vicinity of anisotropic critical points in the absence of an electric field [33 to 361.…”

Theory of optical spin orientation in silicon

“…He found that the lineshapes are not sensitive to exciton effects at high photon energy. The electroabsorption in indirect gap semiconductor 12,13 and the absorption spectra of multiexciton-impurity complexes 14 were also investigated. Hartman 15 determined the absorption spectra using a parabolic band approximation.…”