High-Performance Planar Thin-Film Thermoelectric Cooler Based on Sputtered Nanocrystalline Bi₂Te₃/Bi_0.5Sb_1.5Te₃ Thin Films for On-Chip Cooling

The development of high-performance thin-film thermoelectric coolers (TFTECs) that are compatible with standard integrated circuit processes and can reduce power consumption is critical to achieving large-scale applications. In this work, we fabricate a planar TFTEC based on nanocrystalline p-type Bi_0.5Sb_1.5Te₃ and n-type Bi₂Te₃ thin films using magnetron sputtering, standard lithography, and postannealing processes. The power factors of the Bi_0.5Sb_1.5Te₃ and Bi₂Te₃ thin films reach 3.63 and 4.28 mW/mK², respectively, and the ZT values reach 0.82 and 0.93, which are comparable to those of bulk TE materials. The radial configuration of the device allows the cold-side thermal resistance to be increased and the hot-side thermal resistance to be decreased, thereby facilitating a substantial cooling temperature difference. Furthermore, the large in-plane contact area helps to reduce device resistance and power consumption. At a heating stage temperature of 360 K and a power consumption of 4.76 mW, the net cooling temperature difference of the TFTEC reaches 4 °C. The maximum temperature difference between the hot end and the cold end is 7.26 °C, while the cold end temperature remains below the ambient temperature. The high-performance planar TFTECs demonstrated in this work exhibit both a high net cooling performance and competitive fabrication cost, rendering them ideal for on-chip hotspot cooling.