Miniaturized Thermoelectric Cooler

Abstract

Vapor-deposited bismuth telluride (n-type) and antimony telluride (p-type) films are used in a micro, column-type, patterned thermoelectric cooler. The optimum number of thermoelectric pairs and operating current are predicted. Such devices contain a number of metal/thermoelectric and metal/elecrical-insulator interfaces. In the analysis, various interfacial resistances (phonon and electron boundary resistances and thermal and electrical contact resistances) have been included. The boundary resistances cause a reduction in the thermal conductivity (desirable) and a reduction in the Seebeck coefficient (undesirable) of the thermoelectric elements. The contact resistances reduce the overall device performance. In the fabrication, the stoichiometry of the deposited thermoelectric films, the patterned film deposition, and the selection of the conducting connectors, are discussed. The thermoelectric films are about 4 μm thick and are deposited on patterned platinum (first trial layer for connectors), which are in turn deposited on oxide coated silicon wafers. The top, suspended connectors that close the electrical circuit are bonded to the surface to be cooled. The non-uniformity of the composition in the thermoelectric films influences the measured Seebeck coefficients. The analysis shows that a coefficient of performance of 0.38 is obtainable for a wireless micro sensor application.