Thermoelectric properties, Shubnikov–de Haas effect and mobility of charge carriers in bismuth antimony tellurides and selenides and nanocomposite based on these materials

Abstract

We describe here the study of the Shubnikov–de Haas effect and thermoelectric properties of p-(Bi0.5Sb0.5)2Te3 single crystals doped with Ga, n-Bi2–xTlxSe3 and p-Sb2–xTlxTe3. Using Fourier spectra of the oscillations we calculated the mobility of charge carriers and its variation upon doping. We found that Ga has a donor effect in p-(Bi0.5Sb0.5)2Te3, Tl is an acceptor in n-Bi2–xTlxSe3 and increases the mobility of electrons, while in p-Sb2–xTlxTe3, Tl is a donor and decreases the mobility of holes. We consider the evolution of the defectiveness of crystals that leads to the observed effects. We also synthesized and investigated nanocomposites of solid solutions Sb2Te3–xSex (0 < x < 1). When Se concentration increases in Sb2Te3–xSex, the concentration of holes decreases. At the same time the Seebeck coefficient decreases. This is not typical for semiconductors but correlates with the earlier data. A theoretical model was developed to calculate simultaneously the dependences of the Seebeck coefficient, Hall...