Formation of Mn4Si7 thin films by solid-phase ion-plasma method and improvement of their thermoelectric and electrophysical properties

Abstract

In this study, Mn₄Si₇ thermoelectric thin films were deposited on Si(111) and SiO₂/Si(111) substrates via magnetron sputtering, and their microstructural as well as electrical temperature-dependent properties were thoroughly investigated. The as-deposited films at room temperature exhibited an amorphous structure, which underwent a phase transition to a polycrystalline state upon annealing at 800 K. This annealing process resulted in a significant reduction of surface defects and the formation of a continuous film composed of nanocrystallites with dimensions in the range of 50–100 nm. The presence of the SiO₂ dielectric layer on the substrate induced distinct variations in the film’s microstructure and density, which in turn affected its electrical resistivity and thermoelectric performance. The enhancement of thermoelectric properties observed during the amorphous-to-crystalline phase transition is attributed to the selective scattering mechanism of charge carriers at nanocluster boundaries. These findings provide a critical foundation for achieving high-performance Mn₄Si₇-based thermoelectric thin films and expand their potential applications in thermoelectric devices, paving the way for the development of next-generation energy conversion materials.