Scattering of free carriers near a phase transition in the solid solution PbTe_1-xS_x

Anomalous scattering of electrons is investigated near a structural phase transition in PbTe_1-xS_x. When the electron density in samples with x=0.05 is changed by two orders, T_c remains unchanged, and the scattering anomaly DR varies in conformity with n. The appearance of anomalous scattering near T_c is attributed to scattering on the pre-ordered clusters (S is an off-center impurity). The change observed in the shape of the DR(T) curve in the region x=0.2 is attributed to the appearance of an infinite cluster. The quenching phenomena observed on rapid cooling of the samples can be due to freezing of nonequilibrium configurations of the clusters. The influence of donor (In, Cd, Cu, Sb) and isovalent (Sn, Ge) impurities on the phase transition in PbTe_1-xS_x is considered.

Keywords: lead telluride sulphide sulfide solid solutions, IV-VI narrow-gap semiconductors, Curie temperature, indium cadmium copper antimony germanium tin, doping, defects, relaxation