Disorder-activated phonon behaviors of the cubic rocksalt-type semiconductor alloy Li (1-x)/2Ga (1-x)/2M xO (M Mg, Zn) prepared by high-pressure and high-temperature method has been studied by Raman scattering analysis. The LO Raman phonon in Li (1-x)/2Ga (1-x)/2M xO was found to exhibit a distinct two-mode behavior. The compositional dependence of Raman frequency, peak-width, and intensity has been discussed. A model associated with a composite mode of the Brillouin zone center and edge phonons combined with phonon dispersion curves determined by first-principle calculations were employed to explain the asymmetric broadening of the LO phonon mode. The broadening and asymmetric Raman line-shape in Li (1-x)/2Ga (1-x)/2M xO can be interpreted as a composite mode of the softening Brillouin zone center mode and the Brillouin zone edge mode.
ASJC Scopus subject areas
- Physics and Astronomy(all)