Observation of Interface between Thermoelectric Material Zn₄Sb₃ and Electrodes by Resistance Scanning and Seebeck Coefficient Mapping Techniques

Abstract

A ready-for-soldering thermoelectric element composed of Zn₄Sb₃ with Ni–Al diffusion barrier layer and Cu electrode was fabricated by means of a hot-press method. Batch-to-batch variation of the resistance of the element was within 7%, the average resistance was 3.23 mΩ and the standard deviation 0.25 mΩ. Annealing effects on the interface structure between the electrodes and Zn₄Sb₃ were investigated using microprobe techniques such as Seebeck coefficient mapping and resistance scanning. The element showed lower Seebeck coefficient and resistivity than those of the pristine Zn₄Sb₃ without the electrodes. After annealing for 3.6 ks, the Seebeck coefficient and resistivity returned to the intrinsic values of Zn₄Sb₃. Increased resistivity was clearly observed near electrode/Zn₄Sb₃ interfaces of all annealed samples. Seebeck coefficient maps also indicated variation near the interfaces, showing good consistency with the resistance variation.