Effect of the polar distortion on the thermoelectric properties of GeTe

First principle calculations are performed to investigate the effect of polar order strength on the thermoelectric properties of GeTe alloy in its rhombohedral structure. Different magnitudes of polarization exhibit a noticeable effect on the thermoelectric properties of GeTe. In particular, polar structures with higher polarization tend to show higher thermoelectric efficiencies. Thus, it is shown that polarization engineering is an important factor in designing efficient thermoelectric devices. In particular, we proposed that high thermoelectric performances could be achieved by growing epitaxial GeTe films that are bi-axially compressed in the directions perpendicular to the polar axis in order to achieve larger polarization states.