High temperature thermoelectric properties of laser sintered thin films of phosphorous-doped silicon-germanium nanoparticles

Silicon-germanium (SiGe) is an important thermoelectric material for high-temperature applications. In this study, we show that the Seebeck coefficient of the laser sintered thin films of phosphorous (P)-doped Si ₈₀ Ge ₂₀ nanoparticles increases from -144.9 μV/K at room temperature to -390.1 μV/K at 873 K. The electrical conductivity increases from 16.1 S/cm at room temperature to 62.1 S/cm at 873 K and demonstrates an opposite trend when compared to bulk nanostructured materials. The thermal conductivity from room temperature to 573 K is essentially constant within the measurement error of our system at ∼1.35 W/m·K. Therefore, if the thermal conductivity follows a similar temperature dependent trend as reported in past scientific literature, the figure of merit of the thin film Si ₈₀ Ge ₂₀ is estimated to be 0.60 at 873 K which is comparable to a value of ∼1 for bulk nanostructured materials. This result indicates that thin film P-doped SiGe can provide comparable performance with bulk nanostructured SiGe materials by using nanoparticle laser sintering as an easier, quicker, and more cost-effective processing method.