Thermoelectric properties of Bi2Se3/Bi2Te3/Bi2Se3 and Sb2Te3/Bi2Te3/Sb2Te3 quantum well systems

Abstract

In this work, we develop a theory of thermoelectric transport properties in two-dimensional semiconducting quantum well structures. Calculations are performed for n-type 0.1 wt.% CuBr-doped Bi2Se3/Bi2Te3/Bi2Se3 and p-type 3 wt.% Te-doped Sb2Te3/Bi2Te3/Sb2Te3 quantum well systems in the temperature range 50-600 K. It is found that reducing the well thickness has a pronounced effect on enhancing the thermoelectric figure of merit (ZT). For the n-type Bi2Se3/Bi2Te3/Bi2Se3 with 7 nm well width, the maximum value of ZT is estimated to be 0.97 at 350K and for the p-type Sb2Te3/Bi2Te3/Sb2Te3 with well width 10 nm the highest value of the ZT is found to be 1.945 at 440 K. An explanation is provided for the resulting higher ZT value of the p-type system compared to the n-type system.