Unrestricted Hartree-Fock cluster calculation of electronic and optical properties of delta-doped n-i-p-i semiconductors - art. no. 235316

The electronic structure of an impurity band (IB) formed by hydrogenlike do nors in the n layer of a delta -doped semiconductor is calculated by quantu m chemistry methods at the concentration n(D)((2))=10(11) cm(-2). which is less than the critical concentration of the metal-insulator transition. The donor-acceptor pair recombination in a deltan-i-deltap-i doped structure s hortly after pulse excitation is analyzed. We demonstrate that electrons in deep energy levels of the LB are much more strongly localized, both parall el and perpendicular to the plane of the delta layer, compared to electrons in shallow levels. The effect manifests in the luminescence peak, where th e transitions at lower energy are suppressed against the higher-energy ones . The radiative recombination is calculated assuming (i) nonrelaxed frozen molecular orbitals, yielding a full width at half maximum (FWHM) 3.5 meV, a nd (ii) a completely relaxed final state with a FWHM of 1.3 meV. The corres ponding experimental value has a FWHM of 2.6 meV. Various methods are used to study the density of states, electron density, localization, and lumines cence.