A novel approach to micro-fabricated thermoelectric generators with SrTiO₃

The growing demand for autonomous, sustainable, and delocalized power sources for low-power-consuming electronic devices is driving a significant research effort on energy harvesting technologies. Among these, micro-thermoelectric generators (µTEGs) emerge as an appealing solution because of the abundance of residual latent heat sources. This paper proposes an approach to combine high-performance thermoelectric oxides with Si-based µTEGs, leveraging the miniaturization and high-density integration of CMOS-like technologies. The approach is applied to the integration of niobium-doped strontium titanate (Nb:STO) thin films on Si-based planar µTEG structures. The Nb:STO-based µTEG achieves a specific power density Γ = 0.36 nW·cm^-2·K^-2 under controlled temperature gradients, which is below state-of-the-art performance probably due to lower electrical conductivity from polycrystalline growth. When the chips were tested under realistic operating conditions - placed on a hot surface at 175°C - a maximum power output of p = 0.07 nW was obtained. Nonetheless, by implementing a technological solution for thermal dissipation, the temperature gradient across the thermoelectric material improved by a factor of 110, resulting in a significantly higher extracted power of p = 7.75 nW.