Structural and thermoelectric properties of SiGe/Al multilayer systems during metal induced crystallization

Abstract

While the process of metal induced crystallization (MIC) is widely used in the fabrication of thin film electronic devices, its application to the field of thermoelectrics is fairly new. Especially its implementation in the field of the classic thermoelectric material SiGe could lead to a low cost approach by combining the benefits of low thermal budget, self-doping, and thin film and sputter deposition compatibility. In this work, samples consisting of SiGe/Al multilayers deposited on aluminum oxide based substrates have been prepared. Special emphasis was put on the ratio of Al to SiGe and the resulting changes in transport properties during annealing. On the one hand a certain amount of Al is needed to ensure a complete MIC process for the SiGe, but on the other hand an excess of Al results in a metallic system with low thermoelectric efficiency. In-situ characterization during annealing of the samples was carried out via x-ray diffraction, electrical resistivity, and Seebeck measurements.

Silicon‐Germanium (SiGe) Nanostructures for Thermoelectric Devices: Recent Advances and New Approaches to High Thermoelectric Efficiency

“…Recently, metal-induced crystallization (MIC) [92,113,114] has proved to be an interesting alternative to reduce the crystallization temperature required for SiGe. This process is based on the growth of the films on substrates with Au [115], Ag [116], Al [117], Ni [118], Cr [119],…”

Thermoelectric Inorganic SiGe Film Synthesized on Flexible Plastic Substrate

“…However, bulk-SiGe, formed by zone leveling (ZL) or hot press (HP) techniques, is generally too expensive, resulting in its use being limited to space applications. Therefore, technologies for forming SiGe thin films on insulating substrates using sputtering, , chemical vapor deposition (CVD), − solid-phase crystallization (SPC), , metal-induced crystallization (MIC), , and electrophoresis deposition (ED) have been developed. If a SiGe layer can be formed onto plastic, it will be possible to create flexible thermoelectric devices with high performance.…”

Thin-film thermoelectric generator based on polycrystalline SiGe formed by Ag-induced layer exchange

“…Conversely, the thin-film formation of SiGe can be achieved easily using various vapor deposition techniques. [4][5][6][7][8][9][10][11][12][13][14][15] Furthermore, mature Si process technologies can be applied, including lithography and Fermi-level control, which are essential for thermoelectric applications. Therefore, SiGe is a promising candidate for thin-film TEGs.…”

“…Thin-film thermoelectric applications of SiGe have been studied using laser sintering, 4 sputtering, 5,6 chemical vapor deposition, [7][8][9][10][11] electrophoretic deposition, 12 solid-phase crystallization, 13,14 and metal-induced crystallization. 15 However, SiGe generally requires high temperatures for crystallization and dopant activation, which strictly limit its application. Metal-induced crystallization with layer exchange (LE) has overcome this problem.…”