High-Temperature Thermoelectric Energy Conversion Devices Using Si-Ge Thick Films Prepared by Laser Sintering of Nano/Micro Particles

Abstract

Silicon-germanium (Si-Ge) is used as a high-temperature thermoelectric material due to its high figure of merit and good thermal stability at high temperatures. This article focuses on the high-temperature thermoelectric energy conversion devices using Si80Ge20 thick films prepared by laser sintering of nano/micro particles. The Si80Ge20 thick films were prepared by ball milling of Si-Ge material to achieve nano/micro particles and then laser sintering to achieve thick films. The device consists of three pairs of n-type phosphorus-doped Si80Ge20 legs and p-type boron-doped Si80Ge20 legs. The maximum temperature difference of 200 K was achieved when the hot-side temperature was 873 K and the cold-side was kept in the air (no water cooling). The corresponding maximum thermovoltage and output-power were 311.6 mV and 15.85 $\mu \text{W}$ . The effective power density was calculated as 8.8 mW/cm2. The performance of the device could be further improved by increasing the hot side temperature to about 1000 °C and cooling the cold side by water circulation, to generate a larger temperature difference. We demonstrate that this novel fabrication method as an easier, faster, and lower-cost way to fabricate the thick film type thermoelectric devices with high performance. Our demonstrated approach will be suitable for thermoelectric devices for large-area applications on arbitrary shapes. The presented method will also find applications for on-chip cooling and powering, which could substitute MEMS-based fabrication methods for $\mu $ -thermoelectric generators (TEGs) or other microthermoelectric modules with a simpler, cheaper, and faster fabrication process.