High temperature Si-Ge alloy towards thermoelectric applications: A comprehensive review

Silicon-Germanium is an excellent and well-proven alloy with wide application in the transistor technology and space industries because of its meritorious features such as easy to form both n- and p-type depending on the dopant, environment friendliness, highly abundant material on earth's crust, high mechanical strength etc. This review article highlights the status, potential, and challenges associated with thermoelectric applications. In spite of the fact that Si-Ge exhibits a complex phase diagram due to the wide separation between the solidus and liquidus line, solid-state synthesis could overcome the difficulties associated with the homogeneity and is an epitome to achieve single-phase alloy. Moreover, the beauty of the method is that the yield of the product is very high. This review article also encompasses the strategies involved to reduce the thermal conductivity of the alloy which is otherwise essential to have high figure-of-merit (zT). It also highlights the importance of bulk nanostructuring, which still embraces the title of highest ever reported zT of both n- and p-type bulk Si-Ge alloy. Towards the end, the review opens up a new avenue for exploring methods to reduce the internal resistance of the Si-Ge unicouple and fabrication of DC-DC booster circuit so that the demand for higher voltage can be realized. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Silicon-Germanium is a proven alloy with wide applications in technology, but faces challenges. Solid-state synthesis overcomes homogeneity issues with high yield and environmental friendliness. Strategies to reduce thermal conductivity and explore new methods are crucial for improving performance metrics.