Impact of Material Properties on Cooling COP of Integrated Thermoelectric Microcoolers

Thermoelectric (TE) microcooling is promising for removing hotspots in integrated circuit chips. The cooling coefficient-of-performance (COP) of the on-chip thin film or superlattice micro-cooler (SLC) is a metric for assessing the energy efficiency of the hot spot removal. The COP is key for lowering total power consumption and minimizing heat sinking requirements. Due to the moderate performance compared to vapor compression cycles, researchers have devoted considerable effort to improving the figure-of-merit (ZT) of the material over the past decade. However, the impact of each of the individual thermoelectric properties has not been studied separately. We report our study based on an analytical model and analysis results that show the intrinsic impact of electrical conductivity, the Seebeck coefficient, and thermal conductivity, while the device thickness and the drive current are optimized for maximizing cooling COP. The results show that the power factor of the TE materials is a more important parameter than thermal conductivity reduction for improving the cooling performance of the on chip SLC.