Kryvulkin I. The concentration anomalies of properties in semiconductor solid solutions based on tin telluride

Object of investigation - semiconducting solid solutions based on lead telluride in the PbTe-MnTe and PbTe-GeTe systems. Aim of investigation - the establishment of behavior dependencies mechanical, galvanomagnetic and thermal properties as functions of composition and temperature of semiconducting solid solutions based on PbTe in the PbTe-MnTe and PbTe-GeTe. Methods of investigation: microstructure investigation, X-ray diffraction, measurements of microhardness, electrical conductivity and the Seebeck coefficient, the Hall effect investigation, the coefficient of thermal expansion, thermal conductivity and heat capacity. Theoretical and practical results: the complex study of the physical properties as functions of composition and temperature of semiconducting solid solutions based on lead telluride in the PbTe-MnTe and PbTe-GeTe systems was performed. It was established that in the range of MnTe and GeTe concentrations ~ 0.75 - 2 mol.%, the isotherms of physical properties exhibit anomalous behavior.The detected anomalies are attributed to critical phenomena accompanying the transition to heavy doping, which can be considered as a concentration phase transition. In the approximation of percolation theory, a model of processes that determine the non-monotonic behavior of the concentration dependences of properties is developed. In the dependences of the specific heat on the composition of PbTe-MnTe and PbTe-GeTe solid solutions, distinct peaks are observed at 0.75 - 2 mol.% of MnTe and GeTe, which confirms the existence of phase transitions. We can to assume that a transition to the impurity continuum can be accompanied by self-organization processes in the impurity subsystem of a crystal. Field of application: physics and material research science of ternary and multinary semiconducting compounds, physics of semiconductors, physics of defects.