Enhancement of the thermoelectric efficiency of PbTe by selective site doping: Effect of group VA impurities

The electronic structure of group VA impurities in PbTe is investigated by first principles calculations. Our findings show that these impurities can act as either donors or acceptors, depending on whether they occupy Pb or Te lattice sites. The impurities introduce a defect state at ∼0.3 eV above the conduction band minimum if they stay at Pb sites, whereas they introduce a state at the edge of the PbTe valence band if they stay at Te sites. The implications of our calculations on the thermoelectric efficiency of PbTe are also discussed.