Effect of the polar distortion on the thermoelectric properties of GeTe

TL;DR

This study uses first-principles calculations to explore how polar distortions in GeTe influence its thermoelectric properties, revealing that polarization engineering can enhance TE efficiency.

Contribution

It demonstrates how varying ferroelectric distortions in GeTe significantly affect its thermoelectric performance, suggesting polarization control as a design strategy.

Findings

Higher polarization modes improve TE efficiency at high temperatures.

Polar structure with {bb}=1.5 shows superior TE performance.

Epitaxial growth can be used to tune properties via biaxial compression.

Abstract

First principle calculations are performed to investigate the effect of polar order strength on the thermoelectric (TE) properties of GeTe alloy in its rhombohedral structure. The variation in the polarization state using various ferroelectric distortions {\lambda} ({\lambda}=0,0.5,1.0,1.25,1.5) allows to change the thermoelectric properties to a large extent. The polar structure with a high polarization mode ({\lambda}=1.5) tends to show a higher TE efficiency than the cubic structure at high temperatures. Thus, polarization engineering may play a key role in designing efficient thermoelectric devices. In particular, high TE performances could be achieved by growing epitaxial GeTe films that bi-axially compress the directions perpendicular to the polar axis, which may help to tune the Curie temperature.