SiGe-based planar thermoelectric thin film micro refrigerators

The continuous improvement of microelectronic devices' performance in recent days have resulted in great challenges in thermal management. Thermoelectric microrefrigerators stand out from other traditional cooling methods such as air or liquid forced cooling, metal heatsink and heat pipe cooling due to its all solid-state, high reliability, low noise level, quick response, cooling ability below ambient and scalable property. Besides toxic problem, conventional microrefrigerators based on heavy metal elements such as Bi₂Te₃ are generally incompatible with microelectronic fabrication process and are therefore challenging for on-chip integration. In this work, we demonstrate the single-stage and two-stage thermoelectric microrefrigerators based on nanograined SiGe thin films in planar configuration with the total dimension of 420×420 µm² and 860×860 µm² respectively. After optimization of thin film properties, adjustment of structure design and contact property improvement, maximum cooling temperatures of 9.3 K and 11.2 K have been achieved by the single-stage and two-stage microrefrigerators respectively with power consumption less than 1 mW.