Giant LO oscillation in the Zn1-xBex(Se, Te) multi-phonons percolative alloys

• Published in: Thin solid films 2004-02, Vol.450 (1), p.195-198
• Main Authors: TITE, T, PAGES, O, AJJOUN, M, LAURENTI, J. P, GOROCHOV, O, TOUMIE, E, MAKSIMOV, O, TAMARGO, M. C
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; General studies of phase transitions; 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; Renormalization-group, fractal, and percolation studies of phase transitions
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2003.10.071

We enrich a percolation-based picture for the basic understanding of the atypical two-modes behavior observed by Raman scattering in the Be-VI optical range of Zn1-xBex(Se,Te) alloys, with contrast in the bond stiffness. The attention is focused on the longitudinal optical (LO) Be-VI spectral region within the percolation regime (0.19 < x < 0.81). Three apparent anomalies are discussed. First the low-frequency component is systematically overdamped. Also, the high-frequency component exhibits a marked red-asymmetry which goes with an apparent blue-shift with respect to the theoretical predictions derived on a conventional one-bondDBone-mode basis. All three apparent anomalies are accounted for by considering a discrete multi-mode description for each of the low- and high-frequency Be-VI components. They basically arise from inter- and intra-component transfer of oscillator strength resulting in the building up of a quasi-unique giant LO oscillation. The transfer comes from coupling via the common LO macroscopic polarization field.