Nanostructured planar-type uni-leg Si thermoelectric generators

We demonstrate the power enhancement of planar-type uni-leg poly-Si thermoelectric generators by nano-patterning. The thermoelectric generators were fabricated on an SOI wafer by a conventional lithography-based process. The size of the phononic nano-patterning (300 nm in period) was designed based on the thermal phonon mean free path spectrum. The thermal conductivity of the Si membrane was reduced by 60% compared with an unpatterned one, which resulted in the doubled thermoelectric figure-of-merit. The nano-patterning increased the temperature gradient in the Si membrane and resulted in a four times higher voltage and ten times larger power density.