Optimization of superlattice thermoelectric materials and microcoolers

The performance of thermoelectric (TE) coolers is determined by the figure of merit of the TE materials ZT. In order to obtain the optimal performance of a superlattice microcooler, both the superlattice structure and the device were optimized in the design and the fabrication process. The thermal conductivities of InGaAs/InGaAsP superlattices with different periodic lengths were measured with the 3 omega method. The result indicates that the superlattice at a certain periodic length has minimal thermal conductivity, which, in general, corresponds to an enhanced ZT. A 1-D model was utilized to investigate the significant parameters in microcoolers. Based on the modeling results, a set of superlattice microcoolers were fabricated. The maximum cooling temperature that was reached is 0.76 degrees C for the optimized cooler at room temperature.