Fabrication and measured performance of a first-generation microthermoelectric cooler

The measured performance of a column-type microthermoelectric 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 mu m, 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 degrees C, are -74 mu V/K and 3.6 x 10(-5) Omega - m (n-type, power factor of 0.15 mW/K-2 - M), and 97 mu V/K and 3.1 x 10(-5) Omega - m (p-type, power factor of 0.30 mW/K-2 - m). The cooling performance of devices with 60 thermoelectric pairs and a column width of 40 mu m. is evaluated under a minimal cooling load (thermobuoyant surface convection and surface radiation). The average cooling achieved is about 1 K. Fabrication challenges include the reduction of the column width, implementation of higher substrate temperatures for optimum thermoelectric properties, and improvements of the top connector patterning and deposition.