The differential cross section for an electron Raman scattering process in a semiconductor quantum well wire (QWW) and in a free-standing wire of cylindrical geometry involving phonon-assisted transitions is calculated for T = 0 K. A complete description of the phonon modes of cylindrical structures embedded in another material, including a correct treatment of the mechanical and electrostatic matching conditions at the surface, is presented. We consider the Fröhlich interaction to illustrate the theory for a GaAs/AlAs system. Electron states are considered to be confined within a QWW with finite and infinite potential barriers. We also assume single parabolic conduction and valence bands. The emission spectra are discussed for different scattering configurations and the selection rules for the processes are also studied. Singularities in the spectra are found and interpreted.

The differential cross-section (DCS) for an electron Raman scattering (ERS) process in a semiconductor quantum wire (QW) of cylindrical geometry is calculated for T=0 K and neglecting phonon-assisted transitions. Electron states are considered assuming complete confinement within the QW. We also assume single parabolic conduction and valence bands. Two kinds of spectrum are discussed: emission spectra DCS as a function of emitted photon energy) and excitation spectra (DCS as a function of incident photon energy). In both cases we analyse the DCS for different scattering configurations. We study selection rules for the processes. Singularities in the spectra are found and interpreted. The ERS studied here can be used to provide direct information about the electron band structure of the system.

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A theory describing multiphonon resonant Raman scattering (MPRRS) processes in wide-gap diluted magnetic semiconductors is presented, with Cd1−xMnxTe as an example. The incident radiation frequency ωl is taken above the fundamental absorption region. The photoexcited electron and hole make real transitions through the LO phonon, when one considers Fröhlich (F) and deformation potential (DP) interactions. The strong exchange interaction, typical of these materials, leads to a large spin splitting of the exciton states in the magnetic field. Neglecting Landau quantization, this Zeeman splitting gives rise to the formation of eight bands (two conduction and six valence ones) and ten different exciton states according to the polarization of the incident light. Explicit expressions for the MPRRS intensity of second and third order, the indirect creation and annihilation probabilities, the exciton lifetime, and the probabilities of transition between different exciton states and different types of exciton as a function of ωl and the external magnetic field are presented. The selection rules for all hot exciton transitions via exciton–photon interaction and F and DP exciton–phonon interactions are investigated. The exciton energies, as a function of B, the Mn concentration x, and the temperature T, are compared to a theoretical expression. Graphics for creation and annihilation probabilities, lifetime, and Raman intensity of second and third order are discussed.

The one-phonon resonant Raman scattering of tetragonal zinc-blende-like semiconductors is presented and applied to II-III 2 -VI 4 ordered-vacancy compounds, in particular to ZnGa 2 Se 4 . The well-known theory of one-phonon resonant Raman scattering in III-V or II-VI polar semiconductors has been extended to the tetragonal symmetry of these materials in the approximation that they can be considered as slightly distorted zinc-blende compounds. This approach is especially valid for the high frequency B + E modes that arise from the zone centre optical mode of the zinc-blende structure and show, in an ordered-vacancy compound, a very small tetragonal splitting. The LO components of these modes, B LO and E LO , are considered. The contribution of the different excitonic transitions to the scattering process is studied. Deformation potential and Fröhlich interaction are considered as exciton-phonon interaction mechanisms. Emphasis is placed in the discussion on aspects related to symmetry lowering. Interference effects between excitonic resonances are also discussed.