0000000000266482
AUTHOR
S. T. Pavlov
Resonant rayleigh scattering in semiconductor structures
A detailed study of the relative role played by localized and/or propagating intermediate excitonic states in, resonant Rayleigh scattering (RRS) is presented for a large set of GaAs quantum well (QW) and bulk structures. We show that the two kinds of states contribute to RRS through different mechanisms. We concluded that RRS occurs via localized states in QW heterostructures, very likely due to localization by the interface roughness, while bulk, crystals turn out to be better candidates for RRS via propagating states.
Elastic light scattering from semiconductor structures: Localized versus propagating intermediate electronic excitations
We present a theoretical study of the relative role of localized and propagating intermediate electronic states in the processes of elastic scattering of light. Only localized excitations lead to isotropic scattering in lowest-order perturbation theory. Inhomogeneous broadening of the optical transition affects the scattering efficiency from the ordered and disordered array of localized states in a qualitatively different way. The propagating electronic excitations may only contribute to elastic light scattering via higher-order processes. The scattering of excitons by impurities or the interface roughness potential is suggested as a mechanism for the contribution of propagating excitations…
Magnetic-field-enhanced outgoing excitonic resonance in multi-phonon Raman scattering from polar semiconductors
A combined scattering mechanism involving the states of free electron-hole pairs (exciton continuum) and discrete excitons as intermediate states in the multi-phonon Raman scattering leads to (1) a strong increase of the scattering efficiency in the presence of a high magnetic field and to (2) an outgoing excitonic resonance: the two features are not compatible when only free pairs (leading to a strong increase of the scattering efficiency under the applied magnetic field) or discrete excitons (resulting in the outgoing resonance at the excitonic gap) are taken into account.
Triple magnetopolarons in quantum wells
We derive the equations for eigenstates and eigenenergies of a triple magnetopolaron in quantum-well structures. An iteration procedure for obtaining the wave function and energy including the contributions of diagrams with crossing phonon lines is given. We show that under conditions of exact resonance the middle energy branch of the triply split magnetopolaron state consists of only two out of three bare states. We suggest the experimental verification of this prediction.
Resonant Rayleigh scattering in quantum well structures
Abstract We report continuous wave experiments on resonant Rayleigh scattering (RRS) performed on high quality GaAs AlGaAs quantum well structures. The simultaneous measurement of the resonant Rayleigh scattering and of the photoluminescence excitation (PLE) allows us to resolve very small differences between the two spectra. We show that, even in very good samples, there is a small but detectable Stokes shift of the RRS profile with respect to the PLE. It is also found that the RRS profile has a smaller linewidth and is sensitive to bound exciton transitions which are not detectable in the PLE. We compare our data with previous findings and discuss possible origins of the Stokes shift.
Magnetic Field-Induced Fano Profiles in the Absorption Coefficient of Semiconductors
A strongly asymmetric, Fano-like resonance profile has been found for magneto-absorption in the states of hot free electron-hole pairs scattered by defects in bulk semiconductors. The renormalization of the absorption profile, compared to that expected from the bare density of states in a high magnetic field, follows from a quasi-one-dimensional character of electronic excitations. The results are valid for absorption by the electronic states of large Landau quantum number where the Coulomb interaction should play a minor role. The resonance shape is in a good qualitattive agreement with experimental observations.
Spatial correlation of laser-generated electrons and holes in quantum wells
The spatial correlation of hot electrons and holes generated by light in a semiconductor quantum well (QW) is studied. For hot electron-hole pairs in a polar material, this correlation is determined by the interaction with LO-phonons. We analyze the distribution F N (r, K) of electrons and holes which are created in a given light absorption process, with respect to their relative separation r and total quasimomentum ħK, after the emission of a number N of LO-phonons. The relationship between the spatial distribution of electrons and holes in these intermediate states and the cross-section of multi-phonon resonant Raman scattering (MPRRS) is established. Spatial correlation effects are stron…