Semiquantitative theory of electronic Raman scattering from medium-size quantum dots

Abstract

A consistent semiquantitative theoretical analysis of electronic Raman scattering from manyelectron quantum dots under resonance excitation conditions has been performed. The theory is based on random-phase-approximation-like wave functions, with the Coulomb interactions treated exactly, and hole valence-band mixing accounted for within the Kohn-Luttinger Hamiltonian framework. The widths of intermediate and final states in the scattering process, although treated phenomenologically, play a significant role in the calculations, particularly for well above band gap excitation. The calculated polarized and unpolarized Raman spectra reveal a great complexity of features and details when the incident light energy is swept from below, through, and above the quantum dot band gap. Incoming and outgoing resonances dramatically modify the Raman intensities of the single particle, charge density, and spin density excitations. The theoretical results are presented in detail and discussed with regard to experimental observations.

Electronic Raman scattering in quantum dots revisited

“…In the former case, no experimental measurements have been performed so far. We expect weak Raman signals in this regime, but there are also many advantages such as, for example, the absence of a luminescence background, a smooth dependence of peak intensities on the excitation energy, etc 10 . On the other hand, in the above band gap excitation regime, our calculations are performed for an excitation window ranging from E gap to E gap +30 meV, where E gap is the effective quantum dot band gap.…”

“…3. It was already mentioned elsewhere 10 that, in our opinion, the main limitation of using these functions in the present context is not related to the well-known lack of correlation effects in the RPA, but to the incomplete description of the density of energy levels in intermediate and final states.…”

“…In the present paper, we review a set of theoretical results on Raman scattering in relatively large quantum dots 9,10,11,12 , which were motivated by the experiments described in Refs. [2,3,4].…”

Selection and jump rules in electronic Raman scattering fromGaAs∕AlxGa1−xAsDelgado1, Gonzalez2, Lockwood3 2005Phys. Rev. BSelf Cite5000View full textAdd to dashboardCite

“…[7]. The greek subindices denote the orbital part of the HF electronic states, while the spin projection is explicitly indicated by the arrow.…”

“…The method and approximations used to obtain the many-body wave functions and energies of the required states are explained in Ref. [7]. Energies and wave-functions of the final excited states are obtained by means of the random phase approximation 8 (RPA).…”