Thermoelectric Characterization of Si/Silicide-Heterostructure Layers Fabricated by RF Magnetron Sputtering

Abstract

Recently, due to the limitation of fuel energy, much attention has been paid to novel energy harvesting systems. Particularly, thermoelectric-based energy harvesting systems have been of great concern due to their high potential for the applications of the internet of things (IoT), healthcare monitoring and wearable systems, leading to a variety of intensive research & development efforts. However, many studies have been limited to toxic materials such as Bismuth Telluride and Lead Telluride. There is also a limitation in depositing the thermoelectric materials made of Bismuth Telluride or Lead Telluride in the form of thin films ranging in thickness from several micro to nano meters. In this paper, we present a study on environment-friendly, non-toxic thermoelectric Si/silicide heterostructure layers. Silicon (Si) material itself has two key parameters, intrinsically low Seebeck coefficient and high thermal conductivity, which means that its figure of merit (ZT) is small. To overcome this drawback, in this work, we apply the so-called “bandgap engineering” concept to the formation of the Si/silicide heterostructure layer, where the ZT value can be further increased conceptually by increasing the Seebeck coefficient by both filtering out low energy electrons and also decreasing the thermal conductivity by suppressing the phonon-phonon scattering. To fabricate Si/Silicide heterostructure layers, we used an RF magnetron sputtering method and a rapid thermal annealing (RTA) process. The fabricated heterostructure layers were analyzed by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Seebeck coefficient analyzer, etc.