Suppression of decomposition in Mg₃Bi₂ thin films by amorphous Si capping for thermoelectric applications

Mg 3 Bi 2 -based materials exhibit high thermoelectric performance, but their poor atmospheric stability hinders practical applications. In this study, we enhanced the stability of Mg 3 Bi 2 thin films by applying an amorphous Si capping layer. The capped films effectively suppressed decomposition of Mg 3 Bi 2 into Bi upon atmospheric exposure, resulting in a stable and higher thermoelectric power factor of over 3.0 μW cm -1 K -2 at room temperature compared to uncapped films. Our results demonstrate that an amorphous Si capping layer not only provides essential atmospheric stability to Mg 3 Bi 2 but also preserves its inherent high thermoelectric properties, advancing its viability for practical applications.