Electrical characteristics and detailed interfacial structures of Ag/Ni metallization on polycrystalline thermoelectric SnSe

Abstract

SnSe is a promising thermoelectric material with a high figure of merit in single crystal form, which has stimulated continuous research on polycrystalline SnSe. In this study, we investigated a metallization technique for polycrystalline SnSe to achieve highly efficient and practical SnSe thermoelectric modules. The Ag/Ni metallization layers were formed on pristine polycrystalline SnSe using various deposition technique: sputter coating Ni, powder Ni and foil Ni by spark plasma sintering. Structural analysis demonstrated that the microstructure and contact resistance could be different according to the metallization process, despite using the same metals. The Ag/Ni metallization layer using foil Ni acted as an effective diffusion barrier and minimized electrical contact resistance (2.3 × 10-4 Ω·cm2). A power loss in the thermoelectric module of only 5% was demonstrated using finite element simulation.