Layer-Structured GaGeTe Compound as a Promising Thermoelectric Material

Due to the existence of weak chemical bonding for a low lattice thermal conductivity, outstanding thermoelectric performances have been frequently realized in semiconducting compounds with a layered crystal structure along the out-of-plane direction. Layer-structured GaGeTe shows a p-type conduction with a theoretical high carrier mobility, owning a great potential for thermoelectric applications. This work focuses on a comprehensive revelation of thermoelectric properties for GaGeTe, and the layered structure leads the hot-pressed pellets to be textured and thereby results in an anisotropy of transport properties. The single parabolic band (SPB) model with acoustic scattering leads to a reasonable assessment of electrical transport properties and a well understanding of underlying physical parameters along the direction perpendicular to that of a hot press. Benefiting from the weak van der Waals bond for a low sound velocity as well as a low lattice thermal conductivity of ∼0.6 W/m K, a peak zT of ∼0.4 is realized for GaGeTe along the parallel direction. This work not only demonstrates this material as a promising thermoelectric but also guides the further enhancements by microstructure engineering.