Enhanced Interfacial Adhesion and Thermal Stability in Bismuth Telluride/Nickel/Copper Multilayer Films with Low Electrical Contact Resistance

Abstract The interfacial property between thermoelectric films and metal electrodes greatly affects the performance and practical application of thin‐film thermoelectric devices. Here, Ni intermediate layer is chosen and inserted into Bi 2 Te 3 /Cu to simultaneously regulate the electrical and mechanical performance of the interface. Meanwhile, Ar/H 2 plasma cleaning is also adopted to optimize the interfacial connection during the sputtering process. Results show the interfacial element diffusion can be effectively blocked after the introduction of Ni interlayer, and the Bi 2 Te 3 /Ni/Cu multilayer thin film performs an excellent interfacial adhesion and maintains a low specific contact resistivity about 2.7 × 10 −6 Ω cm 2 , which can be attributed to the matching of thermal expansion coefficient between Bi 2 Te 3 , Ni, and Cu, and the reduction of lattice mismatch. Furthermore, the Ni interlayer can also alleviate the degradation of interfacial mechanical and electrical properties after 1000 cycles of thermal shock, consequently enhancing the reliability and stability of the interfacial connection. This work provides an effective way to improve the comprehensive performance of multilayer interface in thin‐film thermoelectric devices.