Thermoelectric and galvanomagnetic properties of layered $n$-Bi$_{2-x}$Sb$_{x}$Te$_{3-y}$Se$_{y}$ films

The thermoelectric properties in the temperature range 4.2–300 K and magnetoresistance oscillations in strong magnetic fields at low temperatures are studied in nanostructured layered films of topological thermoelectric materials $n$-Bi$_{2-x}$Sb$_{x}$Te$_{3-y}$Se$_{y}$. It is shown that the thermoelectric figure of merit in layered $n$-Bi$_{2-x}$Sb$_{x}$Te$_{3-y}$Se$_{y}$ films is larger than that in the bulk material due both to an increase in the Seebeck coefficient below room temperature and to a decrease in the thermal conductivity and its weaker temperature dependence. Analysis of the magnetoresistance oscillations is used to determine the parameters of the topological surface states of Dirac fermions and estimate their influence on the thermoelectric properties.