Thermoelectric properties of bipolar diffusion effect on In4Se3−xTex compounds

Abstract

We present thermoelectric properties and electronic structure of the series compounds of In4Se3−xTex (0.0≤x≤3.0). Even if the Te-doping is an isoelectronic substitution, we found that the electron dominated carrier transport in Se-rich region (x≤0.2) evolves into the electron-hole bipolar transport properties in Te-rich region (x≥2.5) from the temperature-dependent thermal conductivity κ(T), Seebeck coefficient S(T), and Hall coefficient RH(T) measurements. The electronic band structures of In4Se3−xTex (x=0.0, 2.75, and 3.0) are not changed significantly with respect to Te-substitution concentrations. From the Boltzmann transport calculation, the electron-hole bipolar effect on thermoelectric transport properties in Te-rich region can be understood by lowering the chemical potential to the valence band maximum in the Te-rich compounds.