SiGe nanowire arrays based thermoelectric microgenerator

Thermoelectric micro/nanogenerators (µTEGs) are potential candidates as energy harvesters to power IoT sensors. This study reports on a thermoelectric micro/nanogenerator with a planar architecture built by silicon micromachining technologies that uses silicon-germanium (SiGe) nanowire (NW) arrays as thermoelectric material. The growth of bottom-up NW arrays by means of Chemical Vapour Deposition - Vapour Liquid Solid growth (CVD-VLS) and their monolithic integration into prefabricated microplatforms are presented. It is shown that SiGe NWs based µTEGs can harvest 7.1 μW/cm2 without any additional heat exchanger, when there is a waste heat source available at a temperature of 200 °C. Since the required power density for many sensing applications is in the range of 10–100 μW/cm2 the results obtained in this work are close to meet expectations.