Synthesis of silicon and molybdenum–silicide nanocrystal composite films having low thermal conductivity

•We synthesized semiconducting composite films of Si and Mo-silicide nanocrystals.•Raman measurements show that the crystallization occurred at ≥ 700 °C.•The diameters of Si and Mo silicide nanocrystals were 8 nm and 11 nm, respectively.•The thermal conductivity was reduced to 2.2 W m− 1 K− 1.

We synthesized semiconducting composite films of Si and Mo–silicide nanocrystals (NCs) by phase separation from amorphous Mo–Si alloy (Si:Mo = 12:1). Raman measurements show that the crystallization occurred at ≥ 700 °C. Transmission electron microscope images show that Si and Mo silicide NCs were grown to average diameters of 8 nm and 11 nm, respectively, by annealing at 800 °C. The electrical resistivity of the composite film is semiconducting (0.2–1.2 kΩ cm at room temperature depending on preparation conditions) and decreases with temperature increase. The thermal conductivity was reduced to 2.2 W m− 1 K− 1 by enhancement of phonon scattering at NC interfaces, suggesting that the composite film is promising as a high-efficiency Si-based thermoelectric material.