Thermoelectric Properties of Silicon Nanowire Array and Spin-on Glass Composites Fabricated with CMOS-compatible Techniques

Silicon nanowires (NWs) are promising thermoelectric materials as they offer large reductions in thermal conductivity over bulk Si without a significant decrease in the Seebeck coefficient or electrical conductivity. In this work, interference lithography was used to pattern a square lattice photoresist template over 2 cm x 2 cm Si substrates. The resulting vertical Si NW arrays were 1 μm tall with a packing density of ~15%, and the diameter of the Si NWs were 80-90 nm. The Si NW arrays were then embedded in spin-on glass (SOG) to form a dense composite material with a measured thermal conductivity of 1.45 W/m-K at 300 K. Devices were fabricated for cross-plane Seebeck coefficient measurements and the Si NW/SOG composite was found to have a Seebeck coefficient of roughly-284 µV/K, which is similar to bulk Si with the same doping. We also report a combined power generation of 29.3 µW from both the Si NW array and Si substrate with a temperature difference of 56 K and 50 µm x 50 µm device area