Low-temperature phase transitions in some quaternary solid solutions of IV-VI semiconductors

TL;DR

This study investigates low-temperature phase transitions in specific quaternary IV-VI semiconductor solutions, revealing their dependence on composition and off-center ion behavior through electrical and X-ray analysis.

Contribution

It provides new insights into phase transition regions and mechanisms in quaternary IV-VI semiconductors, emphasizing the role of off-center ions and substitutional disorder.

Findings

Identified temperature ranges of phase transitions in studied solutions.

Linked phase transitions to off-center S and Sn ions.

Described how composition affects transition temperatures.

Abstract

Samples of PbS$_x$Se$_y$Te$_{1-x-y}$, Pb$_{1-x}$Sn$_x$Te$_{1-y}$Se$_y$, and Pb$_{1-x}$Sn$_x$Te$_{1-y}$S$_y$ quaternary solid solutions were investigated in the 4--200~K temperature range using electrical and X-ray methods. The regions where low-temperature phase transitions occur were established. It was shown that phase transitions in these solid solutions are associated with off-center S and Sn ions. The dependence of the phase transition temperature on the composition of solid solutions can be qualitatively described taking into account the influence of substitutional disorder on the ordering and tunneling of off-center ions.