Enhanced electrical transport properties of PbTe single crystal through Ga substitution synthesized by a Pb-flux method

Abstract

As a promising thermoelectric material at the medium temperature range, PbTe has attracted much attention during the past several decades. In this study, Ga-doped PbTe single crystals were synthesized by a facile Pb-flux method. The electronic structure calculations reveal that Ga substitution can introduce impurity level in the bandgap, which can effectively modulate the carrier concentration and therefore optimize the electrical conductivity. Experimentally, the carrier concentration was modulated from 1.95 to 4.46 × 1019 cm−3 at 300 K. Accordingly, the electrical conductivity reaches a maximum of 1.5 × 105 S·m−1 at 300 K for the sample with x = 0.025. As a result, maximal thermoelectric power factor 3.07 × 10−3 W·m−1·K−2 is attained at 360 K for the aforementioned sample, 62% higher than that of the undoped sample (1.89 ×10−3 W·m−1·K−2). This work provides a viable method to synthetize high-quality single crystal and it also verifies that Ga substitution can significantly improve the electrical transport properties of single crystalline PbTe thermoelectric material.