3D Electrothermal Simulation of Heterostructure Thin Film Micro-Coolers

A 3D electrothermal model is used to simulate and optimize Si/SiGe superlattice heterostructure micro-coolers. The model considers thermoelectric/thermionic cooling, heat conduction and Joule heating. It also includes non-ideal effects, such as contact resistance between metal and semiconductor, substrate/heatsink thermal resistance, the side contact resistance. The simulated results match very well with the experimental cooling curves for various device sizes ranging from 60×60μm² up to 150×150μm². It is found that the key factor limiting maximum cooling is metal semiconductor contact resistance. The maximum cooling could be doubled if we remove the metal-semiconductor contact resistance. The thin film Si/SiGe superlattice micro-coolers can provide cooling power density over 500 W/cm² as compared with a few W/cm² of bulk Bi₂Te₃ themoelectric coolers. This micro-cooler experimentally demonstrated a maximum cooling of 4.5°C at room temperature and 7°C of cooling at 100°C ambient temperature. It is a promising candidate for microprocessor spot cooling.