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 NiAl 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 m3 and the standard deviation 0.25 m3. 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.