Long‐Wave Optical Phonons in InSbSe₃ Layer Single Crystals

Abstract

The possibility of the formation of a new InSbSe3 semiconductor compound was revealed in /1, 2 / on the base of a physico-chemical analysis and the state diagram of the In Se -Sb2Se3 system. The long-wave optical phonons of In2Se3 and Sb2Se compounds crystallizing in tetragonal ( CjV space group) and in orthorhombic (Dzh space group) structures were investigated elsewhere /3 t o 5 /.The present note shows experimental results on the IR-reflection spectra ofInSbSe layer crystals at E'l polarization. The InSbSe3 polycrystals were synthesized both from In2Se3 and Sb2Se3 compounds and the particular elements taken in stoichiometric relations. The synthesis was carried out at Tall00 K , The synthesized homogeneous polycrystalline mass of InSbSe3 was used for growing the given crystals by the Bridgman method. Optimum conditions for crystals growth were chosen experimentally. W e were successful in obtaining layer single crystals with natural mirror surface easily spalled along the cleavage plane. The reliability of InSbSe3 production was confirmed by differential thermal, X-ray, and chemical analysis.The IR-reflection spectra of InSbSe3 were recorded from the plane of the layer in the frequency range of 80 to 400 cm-l using a long-wave vacuum diffraction IRspectrometer (with a tray section behind the monochromator) with a resolution of 1 cm . The concentration of free carriers did not exceed 10l6 ~m -~. Therefore, their influence on the reflection was found not to be considerable.shows the reflection spectrum of InSbSe3 at zl $ taken at room temperature. The analysis of the spectra carried out by the Kramers-Kronig method allowed to calculate the spectral dependences of the imaginary part of the dielectric constant E ( v ) and the energy loss function Im(l/E(v)) (