Effects of colored disorder on the heat conductivity of SiGe alloys from first principles

TL;DR

This study uses first-principles calculations to show that introducing spatially correlated disorder in SiGe alloys significantly reduces thermal conductivity, potentially boosting thermoelectric efficiency.

Contribution

It provides a detailed ab initio analysis of how colored disorder affects heat conduction in SiGe alloys, a novel approach for thermoelectric material optimization.

Findings

Colored disorder suppresses thermal transport in SiGe.

Up to fourfold increase in thermoelectric figure of merit.

First-principles methodology applied to disorder effects.

Abstract

Semiconducting alloys, in particular SiGe, have been employed for several decades as high-temperature thermoelectric materials. Devising strategies to reduce their thermal conductivity may provide a substantial improvement in their thermoelectric performance also at lower temperatures. We have carried out an ab initio investigation of the thermal conductivity of SiGe alloys with random and spatially correlated mass disorder employing the Quasi-Harmonic Green-Kubo (QHGK) theory with force constants computed by density functional theory. Leveraging QHGK and the hydrodynamic extrapolation to achieve size convergence, we obtained a detailed understanding of lattice heat conduction in SiGe and demonstrated that colored disorder suppresses thermal transport across the acoustic vibrational spectrum, leading to up to a 4-fold enhancement in the intrinsic thermoelectric figure of merit.