Measured Performance of a Micro Thermoelectric Cooler

The measured performance of a column-type micro thermoelectric cooler, fabricated using vapor deposited thermoelectric films and patterned using photolithography processes, is reported. The columns, made of p-type Sb₂Te₃ and n-type Bi₂Te₃ with an average thickness of 4.5 μm, are connected using Cr/Au/Ti/Pt layers at the hot junctions, and Cr/Au layers at the cold junctions. The measured Seebeck coefficient and electrical resistivity of the thermoelectric films, which were deposited with a substrate temperature of 130°C, are −74 μV/K and 3.6×10⁻⁵Ω-m (n-type), and 97 μV/K and 3.1×10⁻⁵Ω-m (p-type). The cooling performance of devices with 60 thermoelectric pairs and a column width of 40 μm is evaluated under a minimal cooling load (thermobuoyant surface convection and surface radiation). The temperatures of the cold and hot surfaces are obtained with an infrared camera. The average cooling achieved is about 1 K. The measured overall electrical resistance ranges from 51 to 58 Ω. Current challenges include the reduction of the column width, implementation of higher substrate temperatures for optimum thermoelectric properties, and improvements of the top connector fabrication.