Theoretical study on power factor of Si/Ge multi-layer thermoelectric micro-cooler

Thermoelectric (TE) micro-cooling is expected to solve the reliability problem caused by rapidly increasing packaging density of IC chips, but as the characteristic length approaching de Broglie wavelength of carriers, electrical transport will show great size effects, and consequently affect power factor, which is the numerator of TE figure of merit. In this paper, power factor of Si/Ge multi-layer TE micro-cooler has been investigated by 2-D Monte Carlo (MC) simulator GNU Archimedes. The results show that, as the thickness of monolayer approaching several nanometers, the quantum effects show great impact on electrical transport, causing electrical conductivity increase of about an order of magnitude, and Seebeck coefficient decrease of about 40% , hence, optimized thickness of multi-layer structures can make full use of quantum effects to enhance the power factor of TE devices.