Development of a Thermoelectric Energy Generator Chip of Small Layout and High Power/Voltage Factors by Foundry Service

Abstract

Thermoelectric energy generator (TEG) is a device which is used to convert temperature difference between the hot and cold junctions into electrical energy. This paper aims at developing a TEG chip of small layout 5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> having three 2.01 mm × 0.72 mm cells in a total of 10080 thermocouples by semiconductor foundry service (TSMC) for the advantages in batch production, low cost, and scalability. The design has the unique features to improve TEG performance by having (1) thin-film polycrystalline silicon-germanium Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.9</sub> Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</sub> layer for higher thermoelectric conversion efficiency, (2) isolation cavity for better thermal insulation, and (3) structural support for improved thermocouple dimensional stability. It is shown that the TEG chip can deliver power factor 0.125μ W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and voltage factor 25.91 V/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> K. The experimental verification demonstrates that the 5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip has output power 2.083μ W and voltage 3.4 V at 20 K temperature gradient. This is by far the TEG design with best thermoelectric performance implemented by the semiconductor foundry service.