(Invited) Cavity-Free Micro Thermoelectric Energy Harvester with Si Nanowires

• Published in: ECS transactions 2019-04, Vol.89 (3), p.95-110
• Main Authors: Watanabe, Takanobu, Tomita, Motohiro, Zhan, Tianzhuo, Shima, Keisuke, Himeda, Yuya, Yamato, Ryo, Matsukawa, Takashi, Matsuki, T.
• Format: Article
• Language: English
• ISSN: 1938-5862; 1938-6737; 1938-6737; 1938-5862
• DOI: 10.1149/08903.0095ecst

We present a new design of silicon-based micro thermoelectric generator, which utilizes silicon nanowire as the thermoelectric leg. It is driven by a steep temperature gradient exuding around a heat flow perpendicular to the substrate, and the silicon nanowires are not suspended on a cavity etched on the substrate. The power density is scalable by shortening the silicon nanowire to sub-μm length, which was experimentally demonstrated and tens of µW/cm2-class power generation was achieved at an externally applied temperature difference of only 5 K. A numerical discussion shows that the thermoelectric power can be drastically enhanced by suppressing the thermal resistance at the entire substrate. Thus, there is a plenty of room at the micro or submicrometric scales for realizing thermal energy harvesting devices with high power densities.