On-chip energy harvesting using thin-film thermoelectric materials

Recent advances in superlattice based thermoelectric (TE) materials hold promise for realizing thin-film TE modules that can be embedded inside a chip package. Significant research effort has been devoted towards evaluating the feasibility of embedded thin-film TE modules for hot-spot cooling applications. Note, these embedded TE modules can also harvest electrical energy from the waste heat dissipated by the chip. In this work, we explore the on-chip energy harvesting capabilities of Bi₂Te₃/Sb₂Te₃ superlattice based TE materials using rigorous finite element simulations. In addition, an inductive DC-DC power converter was designed for up-converting the output voltage of the TE module. The end-to-end conversion efficiency of this harvesting system has been optimized through the co-design of TE module and its power converter. Using the optimized harvesting system, we show that it is possible to harvest up to 4mW from a 3mm² hot-spot with a heat-flux of 200W/cm². Our results indicate that designing the TE module and its power converter independently could lead to a sub-optimal system. In addition, the contact parasitics in the TE module degrade the intrinsic performance of the TE material by as much as 3x. However, when the contact parasitics in the TE module are reduced, the system can suffer from increased resistance mismatches as well as conduction power losses in the converter circuit. Therefore, even if contact parasitics are reduced, it may not provide a significant improvement in the energy harvesting performance at the system level.