Micro-thermoelectric cooler: interfacial effects on thermal and electrical transport

The flows of heat and electricity in a column-type micro-thermoelectric cooler are analyzed by modeling the various interfacial resistances. Electron (barrier tunneling) and phonon (diffuse mismatch) boundary resistances at the thermoelectric/metal interface, and thermal non-equilibrium between electrons and phonons adjacent to this interface (cooling length), increase the thermal conduction resistance and decrease the Seebeck coefficient of the thermoelectric elements. These in turn reduce the device cooling performance, which is also affected by the thermal and electrical contact resistances at the thermoelectric/metal and metal/electrical-insulator interfaces. To produce a temperature drop of 10 K with a cooling load of 10 mW, the optimum number of thermoelement pairs, operating current, and coefficient of performance, based on vapor deposited 4 μm thick films of Bi2Te3 and Sb2Te3, are predicted for a micro-thermoelectric cooler operating with a 3 V battery.