One‐ and Two‐Phonon Raman Scattering in Ternary Phosphides ZnSiP₂, ZnGeP₂, CdSiP₂

Abstract

Abstract One‐ and two‐phonon Raman scattering (RS) of orientated single crystals of ZnSiP 2 , ZnGeP 2 , and CdSiP 2 are investigated. For the first time in ZnSiP 2 the lattice vibrations B 2 (L/T) 146/145 and B 1 466 cm −1 are observed, and the values of L–T splitting of polar modes are determined. It is concluded that in crystals of ZnGeP 2 , ZnSiP 2 , and CdSiP 2 a completely symmetric component of the second‐order RS spectra is formed by overtones and gives the distribution of the phonon state density of the lattice of these compounds. This distribution is determined in the main by the points Λ, T, N of Brillouin zone and has the general form for all compounds investigated. An estimation is given of the frequencies ofinactive A 2 ‐phonons in ZnGeP 2 , ZnSiP 2 , and CdSiP 2 .