Decoupling opposed thermoelectric properties.

We create GeTe/Sb 2 Te 3 multilayer thin films by alternating GeTe and Sb 2 Te 3 to enhance thermoelectric properties. Crystal structure of the sample was characterized from amorphous to crystalline via annealing. The GeTe/Sb 2 Te 3 multilayer thin film can significantly improve thermopower factor from ∼0.1 μW/mK2 to 815.1 μW/mK2 because the interfacial effect breaks down the trade-off between Seebeck coefficient and conductivity. GeTe/Sb 2 Te 3 exhibits high Seebeck coefficient while maintaining large electrical conductivity under proper annealing at 575 K. Thus, a high power factor of 815.1 μW/mK2 obtained by the multilayer structure, which blocks carriers and rationally tunes the carrier density, leads to an enhanced Seebeck coefficient and power factor for thermoelectric devices. Improvement of electrical conduction originates from interfacial bonding and intermixing at a particular thickness ratio during element diffusion process. Results of microstructure characteristics revealed that the existence of hexagonal Ge 2 Sb 2 Te 5 phases may drive the improvement of thermoelectric performance and provide us with a new way of enhancing thermoelectric devices. [ABSTRACT FROM AUTHOR]