Analysis of high-temperature degradation mechanisms at the interface between bismuth telluride and metals and their effect on contact resistance increase

Interfacial reliability of thermoelectric generation (TEG) devices with multilayered material structure is a crucial factor affecting conversion efficiency and device reliability. Previous work demonstrated that specific contact resistivity (ρc) between barrier metals/Bi2Te3 interfaces increased with temperature. Furthermore, results showed that the Ti/Bi2Te3 interface had the lowest ρc at 298 K, whereas the Ni/Bi2Te3 interface exhibited the lowest ρc at 378 K. To investigate the cause of the temperature dependence of ρc with barrier metals, we analyzed several interfacial phenomena after the measurement at 298 and 378 K. As a result, Ag diffusion into Bi2Te3, distortion of the barrier metal, and interfacial alloying were observed under the high temperature. These interfacial degradation phenomena were attributed to thermal stresses. Additionally Ag diffusion increased in the order of Ni < Ti < Cr. Therefore, the results of this study provide unique insights into the degradation mechanisms of material interfaces in TEG devices under high-temperature conditions and clarify the relationships between interfacial deterioration and specific contact resistivity increases.