Multiphonon resonant Raman scattering in the semimagnetic semiconductor Cd1−xMnxTe: Fröhlich and deformation potential exciton–phonon interaction

• Published in: Journal of physics. Condensed matter Vol. 15; no. 19; pp. 3225 - 3248
• Main Authors: Riera, R, Rosas, R, Marín, J L, Bergues, J M, Campoy, G
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 21.05.2003; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Exact sciences and technology; Exciton-mediated interactions; Excitons and related phenomena; Iii-v and ii-vi semiconductors; Infrared and raman spectra and scattering; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Inorganic compounds; Resonance Raman scattering; Strong interactions; Manganese tellurides; Ternary compounds; Differential cross sections; Transition element compounds; Magnetic field effects; Quantization; Excited states; Experimental study; Semimagnetic semiconductors; Energy gap; Zeeman effect; Deformation potential; Exciton phonon interaction; Multi-phonon processes; Cadmium tellurides; Interaction potentials; Energy-level splitting; Exchange interactions
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/15/19/323

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 *wl is taken above the fundamental absorption region. The photoexcited electron and hole make real transitions through the LO phonon, when one considers Frohlich (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 *wl 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.