EFFECT OF LIFETIME BROADENING ON RESONANT BRILLOUIN-SCATTERING IN ZNTE AND ZNSE

Resonant Brillouin scattering by fast-TA phonons in ZnTe and ZnSe has been studied by using an acoustic domain injection method. Two kinds of ZnTe and ZnSe crystals have been used to investigate some effects of the crystalline imperfections on the dispersion of the Brillouin scattering cross sections. The measurements have been made at room temperature and 77 K. It has been found that the Brillouin scattering cross sections are affected strongly by the damping of the intermediate electronic states and that the damping energy does not depend on the temperatures but on the kinds of the crystals. The damping energy of the high-quality ZnTe (ZnSe) determined from resonant Brillouin scattering is varGamma=26 meV (44 meV) at 77 K, which is very large compared with the value of varGamma≃2 meV (3 meV) obtained from reflectance spectrum. The result are interpreted in terms that the damping is caused mainly by an interaction of the intermediate electronic states with the high-intensity acoustic phonon domains and the crystalline imperfections. © 1979 The Japan Society of Applied Physics.