Observation of a Strong Decoupling Phenomenon in Pt/Si Hybrid Structures for In-Plane Thermoelectric Properties

Abstract

The performance of thermoelectric (TE) materials is limited by the intrinsic coupling of the Seebeck coefficient and the electrical conductivity such that an increase in one leads to a decrease in the other with respect to the carrier concentration. This coupling makes it particularly difficult to enhance the TE power factor in TE materials. In this study, we added a Pt top layer over a silicon wafer, forming a hybridized Pt/Si structure to drive a strong decoupling of the Seebeck coefficient and electrical conductivity. The results show that the electrical resistance in the Pt/Si hybrid structure decreased by 94 times compared to that of a single-layer lightly doped Si substrate at 300 K, while the Seebeck coefficient in the hybrid structure decreased slightly compared to that of the single layer. The remarkably high TE performance of the Pt/Si hybrid structure is brought about by the hybridization of the intrinsic high-conductivity Pt layer and the high-Seebeck coefficient Si substrate. In addition, we demonstrate that this novel and effective decoupling method enables the assessment of the in-plane intrinsic Seebeck coefficient of a lightly doped Si wafer, which typically has an electrical resistance that is extremely high to measure the Seebeck coefficient even with a high-resolution voltmeter. These results represent a significant advancement in the understanding of electrical transport in TE materials, which will invigorate further research on Si-based devices for realizing large-area watt-scale TE generation at room temperature. © 2022 American Chemical Society.