Epitaxial SiGeSn Alloys for CMOS-Compatible Thermoelectric Devices

Abstract

The integration of thermoelectric devices into mainstream microelectronic technological platforms could be a major breakthrough in various fields within the so-called Green-IT realm. In this article, the thermoelectric properties of heteroepitaxial SiGeSn alloys, an emergent CMOS-compatible material system, are evaluated to assess their possible application in thermoelectric devices. To this purpose, starting from the experimentally low lattice thermal conductivity of SiGeSn/Ge/Si layers of about ∼1 to 2 W/m·K assessed by means of 3-ω measurements, the figure of merits are calculated through the use of Boltzmann transport equation, taking into account the relevant intervalley scattering processes, peculiar of this multivalley material system. Values for the figure of merit ZT exceeding 1 have been obtained for both p- and n-type material at operating temperatures within the 300-400 K range, i.e., at typical on-chip temperatures. In this interval, the predicted power factor also features very competitive values on the order of 20 μW/cm ·K2. Our finding indicates that this emergent class of Si-based materials has extremely good prospects for real-world applications and can further stimulate scientific investigation in this ambit.