Shevchuk M. Crystal chemistry and thermodynamics of point defects in semiconductor crystals of samarium monosulfide and its analogues

This paper investigates defect subsystem of samarium monosulfid crystals and undoped and doped by rare-earth elements (Sm, Gd, Tm) crystals of lead telluride. Equilibrium values of concentration of chalcogen vacancies and antistructural samarium atoms in semiconductor and metallic phase of SmS at a given temperature and chemical composition were calculated for SmS crystals by minimizing the thermodynamic potential of the crystal. The dependence of electrons effective mass on their concentration in the samarium monosulfid conductive d-band was determined based on the experimental dependences of Hall concentration on temperature. The calculation of the concentration of point defects and free charge carriers in metallic and semiconductor phase of samarium monosulfid single-crystal, which is in equilibrium condition with a pair of metal, was conducted. The temperature dependence of the solidus line of the excess metal was defined. Based on the crystal model of the lead telluride defect subsystem, which takes into account vacancies in anionic and cationic sublattices, dependencies of the concentration of point defects and free charge carriers and the deviation degree from stoichiometry in PbTe crystals depending on the technological parameters of two-temperature annealing - annealing temperature T and vapor pressure of tellurium PTe were calculated. For doped crystals PbTe: Sm, PbTe: Gd and PbTe: Tm models of defect subsystems are proposed and thermodynamic parameters of impurity atoms introduction in the lattice are calculated.