Regular Article

Mg-Ag-Sb thin films produced by solid-state reactive diffusion

¹ Aix-Marseille University ‑ CNRS, IM2NP Faculté des Sciences de Saint-Jérôme case 142, 13397 Marseille, France
² LASMAR, University of Moulay Ismail, Faculté des Sciences, 11 201 Meknes, Maroc

^* e-mail: n.oueldna@gmail.com

Received: 28 January 2023
Received in final form: 9 March 2023
Accepted: 15 March 2023
Published online: 28 April 2023

Abstract

α-MgAgSb is a tellurium-free thermoelectric material that exhibits good thermoelectric properties near room temperature. Being made of relatively abundant elements compatible with the complementary metal oxide semiconductor (CMOS) technology, it is considered as a possible solution for the development of high-efficiency thermoelectric devices for heat waste harvesting in microelectronic setups. This study presents a first attempt to investigate the structural properties of MgAgSb thin films prepared by solid-state reactive diffusion. X-ray diffraction (XRD) was used to follow phase formation in thin films, first, in the case of the binary Ag₃Sb and Mg₃Sb₂ compounds, and then, in the case of the ternary system Mg-Ag-Sb. For the later, in situ XRD was used to follow real-time phase formations during the reaction of the bilayerAg₃Sb/Mg₃Sb₂. The results show that the phase α-MgAgSb can be produced by reactive diffusion at the interface of the bilayer. Furthermore, the three phases α, β, and γ are shown to coexist at 360 °C, which can be the result of the thin film geometry (surface and interface effects) or due to a different stoichiometry between these three phases contrasting with usual belief. At temperatures higher than 450 °C, γ-MgAgSb is the only phase stabilized in the film. This study serves as a benchmark for the production of pure α-MgAgSb thermoelectric thin films by reactive diffusion.