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 Bi2Te3/Cu to simultaneously regulate the electrical and mechanical performance of the interface. Meanwhile, Ar/H2 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 Bi2Te3/Ni/Cu multilayer thin film performs an excellent interfacial adhesion and maintains a low specific contact resistivity about 2.7 × 10−6 Ω cm2, which can be attributed to the matching of thermal expansion coefficient between Bi2Te3, 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.

Interfacial Stability in Bi2Te3 Thermoelectric Joints

“…Contact resistivity can be affected by many factors including the crystallinity of the metal layer, the surface cleanness and roughness of the substrates, and the deposition methods. It has been reported that high crystallinity and smooth interface yield low contact resistivity. , If the metal layers were deposited by sputtering and in contact with Bi 2 Te 3 , the contact resistivities for the as-deposited samples are from 10 –10 to 10 –8 Ω·m 2 . − Applying Ar plasma to clean the Bi 2 Te 3 surface prior to metal deposition and annealing the whole joints at 100 °C for 2 h can further reduce the contact resistivity to 10 –12 Ω·m 2 . By using E-beam evaporating or electroplating methods to deposit the metal contacts, the contact resistivity would be around 10 –11 to 10 –8 Ω·m 2 . − …”

Wearable Thermoelectric Materials and Devices for Self‐Powered Electronic Systems

“…Deng et al. [ 237 ] developed a strategy to optimize the interfacial connection of the Bi 2 Te 3 film by introducing an Ni layer between the Bi 2 Te 3 film and the Cu film electrode. Ar‐H 2 plasma cleaning was used to optimize the interfacial connection during the sputtering process.…”

“…For typical Bi 2 Te 3 -based devices, a thin nickel layer of 0.5-10 mm is usually employed through electrochemical deposition, electroless plating, or magnetic sputtering before the soldering process. Deng et al [237] developed a strategy to optimize the interfacial connection of the Bi 2 Te 3 film by introducing an Ni layer between the Bi 2 Te 3 film and the Cu film electrode. Ar-H 2 plasma cleaning was used to optimize the interfacial connection during the sputtering process.…”

Methods for investigation of electrical contact resistance in a metal film--semiconductor structure

“…Low values of contact resistance in semiconductormetal contact structure significantly complicate its experimental determination. The method of contact resistance measurement similar to well-known method of TLM (Transmission line method) [8,[15][16][17][18] is proposed in this study.…”