Enhancing mechanical and thermoelectric performance of alloy for chip-scale refrigeration

The advancement of information technology necessitates efficient thermal management for chips to ensure stable information transmission. Meanwhile, the thermal management technology must be vibration-free and easily miniaturized to accommodate increasingly integrated chip modules.

Peltier coolers (PCs) based on the thermoelectric (TE) effect have emerged as one of the most promising solutions for chip-scale refrigeration, garnering increasing attention in recent years. Currently, bismuth telluride (Bi₂Te₃) alloy remains the only candidate material available for commercial PCs.

Unfortunately, the layer-structured Bi₂Te₃ is connected by van der Waals forces, and thus exhibits poor mechanical properties, posing great challenges in miniaturization. Therefore, enhancing both the mechanical strength and TE performance of bismuth telluride alloy is crucial in the miniaturization and integration of PCs.

To address these challenges, Professor Jing-Feng Li’s group at Tsinghua University has published a research article in the National Science Review, where a novel microstructure modulation strategy is proposed for Bi₂Te₃ alloy to effectively enhance both the mechanical and TE performance. This advancement ultimately enables the microfabrication of high-performance PCs.

An annealing and hot forging process was developed to promote densification while implementing dislocation strengthening. Additionally, the dispersion strengthening was induced by the incorporation of SiC nanoparticles. These modified microstructures can not only improve the mechanical properties but also regulate the charge carrier and phonon transport.

Subsequently, by optimizing the Te content via a compositional modulation strategy, the TE performance was further enhanced while maintaining the superior mechanical strength required for precision machining purposes. Consequently, efficient PCs with extremely small dimensions were successfully prepared from this ‘strong’ Bi₂Te₃ alloy.

Notably, the aforementioned optimization strategy is not limited to Bi₂Te₃ alloy but is also applicable to other TE systems. This breakthrough shows great potential for solid-state cooling technologies in small spaces, and offers new opportunities for miniaturized refrigeration devices, further advancing related industries.