Thermoelectric Properties of Stressed P-Doped Polycrystalline Silicon Hollow Nanotubes Available to Purchase

Thermoelectric generators have the potential to efficiently convert waste heat into valuable electrical power. Nanoengineering techniques have emerged as a promising solution to enhance the thermoelectric properties of abundant and inexpensive materials like silicon, in contrast with the scarce, toxic, and expensive conventional bulk materials. Recently, a novel class of nanostructured materials in the form of extensive, paper-like fabrics composed of nanotubes has been developed, offering a cost-effective and scalable approach to thermoelectric power generation. In this study, the fundamental properties of these individual nanotubes have been investigated and correlated with the nanostructure’s intrinsic strain for the first time. Transmission electron microscope analysis was used to morphologically characterize the thickness of the polycrystalline silicon and the SiO₂ layers. Raman spectroscopy revealed the partially amorphous nature of the film and showed an intrinsic tensile stress of ∼500 MPa in the polycrystalline layer. Finally, electrothermal measurements using microfabricated suspended nitride membranes were carried out to characterize the thermoelectric properties of these nanotubes, namely: their thermal and electrical conductivities. Thermal conductivities ranging from 2.5 to 6.8 W/m·K and electrical conductivities of 21–219 S/cm were obtained.