Miniaturization of a thermoelectric device ca

image: figure. (a) Magnified view of a π junction consisting of two types of thermoelectric layers connected by a metal electrode. (b) Photograph of the thermoelectric device consisting of a series of junctions.
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Credit: National Institute of Materials Science Isao Ohkubo [email protected]

Using a semiconductor microfabrication technology, a research team consisting of NIMS, AIST and the University of Tsukuba has succeeded in developing a thermoelectric device consisting of a series of π-junctions, each composed of two types of thermoelectric layers connected by a metallic electrode layer. (figure (a)). This device demonstrated the ability to generate voltages in excess of 0.5 V and met a criterion for certain Internet of Things (IoT) devices.

Thermoelectric conversion modules designed for IoT and other electronic devices must be integrated into these devices. Most previously developed versions of these modules were made of bulk materials, which are not compatible with miniaturization and integration. The output voltages of thermoelectric conversion modules and devices generally decrease as their size decreases. One approach to solve this miniaturization related problem is to create a series of junctions in a thermoelectric device. This research team created a thermoelectric device using a semiconductor microfabrication technology that can be used to produce micro-scale π junctions with a high degree of precision.

This research team fabricated an in-plane thermoelectric device (Figure (b)) consisting of a dense array of π junctions, each composed of a p-type Mg2sn0.8ge0.2 thin film with high thermoelectric generation efficiency and low electrical resistance, an n-type bismuth layer, which can be produced at room temperature. Despite its small size, this device, equipped with an array of 36 small π junctions, was capable of generating voltages in excess of 0.5 V, meeting a criterion for certain operations of IoT devices.

The technique used in this research to create smaller, more compact thermoelectric devices can be used to develop new IoT and other electronic products integrated with thermoelectric devices.

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This research was supported by the JST-Mirai project entitled “Utilizing magnetism to development high-performance thermoelectric materials and devices” (project leader: Takao Mori, project number: JPMJMI19A1).

This research was published in Materials Today Energy, an online journal, on June 18, 2022 (URL: https://doi.org/10.1016/j.mtener.2022.101075). In the figure above, a photo from this publication has been used with some adjustments.


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