Observation of Local Modes in Pb_1−xSn_xTe Doped with Group III Elements (In and Ga)

Abstract

Pb_1−xSn_xTe crystals doped with group III elements (In and Ga) exhibit absorption bands at 160 cm⁻¹ and 187 cm⁻¹ in the far-infrared region with In-doped and Ga-doped samples, respectively, which are almost independent of temperatures and tin compositions. These bands are ascribed to the local vibrational modes of In and Ga tons and the ratio of the frequencies could be explained by a simple XY₆ molecular model.