Thermoelectric transport in zinc antimonide ZnSb

Abstract

Transport equations for phonons and electrons are solved to understand the thermoelectric transport in ZnSb. Inherent poor bonding characteristics are reflected in the low frequencies and low group velocities of phonons estimated within the harmonic approximation. Low-frequency optical branches overlap with the acoustic branches, increasing the scattering phase space. Estimated mode Grüneisen parameters indicate an anharmonic system, which is also reflected in the low self-consistent phonon lifetimes. All these factors contribute to the low thermal conductivity of ZnSb. The optimum doping concentration for the thermoelectric figure of merit is approximately 5 × 1018 per cm3. There is an asymmetry in the distribution of the density of states near the band edges, which also contributes to the hole-dominated thermoelectric transport in the intrinsic region.