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Optical Phonons in GaS 1‐x Se x Layer Mixed Crystals
Author(s) -
Gasanly N. M.,
Goncharov A. F.,
Melnik N. N.,
Ragimov A. S.
Publication year - 1983
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221200115
Subject(s) - brillouin zone , phonon , raman spectroscopy , lattice (music) , crystal (programming language) , materials science , dispersion (optics) , spectral line , condensed matter physics , raman scattering , brillouin scattering , molecular physics , optics , crystallography , chemistry , physics , optical fiber , astronomy , computer science , acoustics , programming language
Abstract Measurements are made of polarized Raman scattering and infrared reflection spectra of twenty two compositions of GaS 1 ‐ x Se x layer mixed crystals grown by the Bridgman method. Besides the usual one‐mode and two‐mode behaviours of phonon modes, a number of more complex dependences characterized by the appearance of additional bands in the spectra of mixed crystals are observed. Their appearance is accounted for by the uncovering of the Brillouin zone due to the disturbance of the periodicity of the crystal lattice of mixed crystals. Specifically, for modes with a low dispersion in the Brillouin zone the additional modes are interpreted as vibrations of cells having mixed compositions. A number of anomalies are revealed in the concentration dependences of intensities and frequencies of optical phonons, which are attributed to the β → γ and γ → ϵ polytype transformations at x ≈ 0.6 and x ≈ 0.97, respectively.