Silicon nanostructures for thermoelectric devices: A review of the current state of the art

Silicon is the most important element of modern semiconductor industry. As a thermoelectric converter material, it would be able to promote applications dramatically since device integration and scaling of the fabrication processes could be borrowed from existing technology. Though the thermoelectric performance of single crystalline silicon is only poor, silicon nanostructures have demonstrated a competitive figure of merit. To make use of these nanostructures, novel device architectures are necessary. This review provides an overview over the physical background of silicon as thermoelectric converter material as well as different nanostructures like nanowires, porous nanomeshes, and nanocrystalline bulk and their thermoelectric properties, focusing mostly on experimental data. Further, different thermoelectric converter device concepts including nanowire device concepts, pn junction thermoelectric generators and integrated spot coolers are discussed and their realization with silicon nanostructures briefly sketched. (a) Nanowires, porous nanomeshes and nanocrystalline bulk with promising thermoelectric material's figure of merit. (b) Innovative device concepts using nanowires or large area pn junctions for thermoelectric heat-to-electricity conversion.