2001/06/06 by J. Pérez‐Conde, J. Perez-Conde, A. K. Bhattacharjee · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Chalcogenide Semiconductor Thin Films #Quantum Dots Synthesis And Properties #Semiconductor Quantum Structures and Devices #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.63.245318
published as Phys. Rev. B 63, 245318 (2001) · Revtex, 24 pages, 7 Postscript figures
arxiv created 2001/06/06 · openalex publication_date 2001/06/06 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The optical spectra of CdSe nanocrystals up to 55 \AA in diameter are analyzed in a wide range of energies from the fine structure of the low-energy excitations to the so-called high-energy transitions. We apply a symmetry-based method in two steps. First we take the tight-binding (TB) parameters from the bulk sp3s* TB model, extended to include the spin-orbit interaction. The full single-particle spectra are obtained from an exact diagonalization by using a group-theoretical treatment. The electron-hole interaction is next introduced: Both the Coulomb (direct) and exchange terms are considered. The high-energy excitonic transitions are studied by computing the electric dipole transition probabilities between single-particle states, while the transition energies are obtained by taking into account the Coulomb interaction. The fine structure of the lowest excitonic states is analyzed by including the electron-hole exchange interaction and the wurtzite crystal-field terms in the exciton Hamiltonian. The latter is diagonalized in the single electron-hole pair excitation subspace of progressively increasing size until convergence. The peaks in the theoretical transition spectra are then used to deduce the resonant and nonresonant Stokes shifts, which are compared with their measured values in photoluminescence experiments. We find that the final results depend on the crystal-field term, the relative size of the surface, and the degree of saturation of the dangling bonds. The results show satisfactory agreement with available experimental data.