Ni/GeTe Interfacial Reactions and Ni-Ge-Te Phase Equilibria

• Published in: Journal of electronic materials 2023-12, Vol.52 (12), p.8019-8029
• Main Authors: Chen, Sinn-wen, Chen, Yi, Yang, He-Cheng, Ho, Cheng-Hsi
• Format: Article
• Language: English
• Subjects: Alloys; Alternative energy sources; Barrier layers; Characterization and Evaluation of Materials; Chemical engineering; Chemistry and Materials Science; Electronics and Microelectronics; Electroplating; Energy resources; Equilibrium; Germanides; Instrumentation; Interface reactions; Intermetallic compounds; Materials Science; Nickel compounds; Optical and Electronic Materials; Original Research Article; Phase equilibria; Solid State Physics; Species diffusion; Substrates; Thermoelectricity; Thickness
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-023-10714-1

GeTe is a mid-temperature thermoelectric compound that has shown promise for use in thermoelectric modules. In this study, the interfacial reactions between Ni and GeTe are carried out to determine the suitability of Ni as a barrier layer. Furthermore, the Ni-Ge-Te phase equilibria isothermal sections at 500°C and 400°C are not available in the literature. They have been determined to provide fundamental information and for better understanding of the Ni/GeTe interfacial reactions. Ni-Ge-Te alloys were prepared and equilibrated at 500°C and 400°C revealing two ternary compounds, Ni 3 GeTe 2 and Ni 5.45 GeTe 2 , and insignificant ternary solubilities in most of the binary compounds. Ni/GeTe couples were prepared by electroplating Ni on the GeTe substrate, and the reaction layer thickness was 71  μ m in the Ni/GeTe couple reacted at 500°C for 24 h. The reaction path was Ni/(Ni 3 Te 2  + Ni)/Ni 3 Ge/(Ni 3 Ge + Ni 5.45 GeTe 2 )/(Ni 5.45 GeTe 2  + Ni 5 Ge 3 )/(Ni 5 Ge 3  + Ni 3 GeTe 2 )/(NiGe + Ni 3 GeTe 2 )/GeTe at 500°C, and was Ni/(Ni 5 Ge 3  + Ni 5.45 GeTe 2 )/(Ni 5 Ge 3  + Ni 3 GeTe 2 )/(NiGe + Ni 3 GeTe 2 )/GeTe at 400°C. Ni was the primary diffusion species in the Ni/GeTe couples at both temperatures. Significant interfacial reactions were observed in the Ni/GeTe couples reacted at 500°C and 400°C, indicating that Ni might not be suitable as a barrier layer. Graphical Abstract