Thermoelectric properties of tin telluride quasi crystal grown by vertical Bridgman method

Abstract

Tin telluride (SnTe), with the same rock salt structure and similar band structure of PbTe alloys, was developed as a good thermoelectric material. In this work, SnTe quasi crystal was grown by vertical Bridgman method, with texturing degree achieved at 0.98. Two sets of samples, perpendicular and parallel to the growth direction, were cut to investigate thermoelectric properties. As a result, a carrier concentration (pH) of ~9.5 × 1020 cm-3 was obtained, which may have originated from fully generated Sn vacancies during the long term crystal growth. The relatively high Seebeck coefficient of ~30 μVK-1 and ~40 μVK-1 along the two directions was higher than most pristine SnTe reported in the literature, which leads to the room temperature (PF) for SnTe_IP and SnTe_OP achieved at ~14.0 μWcm-1K-2 and ~7.0 μWcm-1K-2, respectively. Finally, the maximum dimensionless figure of merit (ZT) values were around 0.55 at 873 K.