Defect structure of Pb-doped Bi2Te3 single crystals

Pb-doped Bi2Te3 single crystals with a Pb concentration of c(Pb) 0 - 9.4 x 10(25) m(-3) were prepared from the elements Bi, Pb and Te of 99.999% purity by means of the Bridgman method. Samples of these crystals were characterized by measurements of the Hall coefficient R-H(Bparallel toc), electrical conductivity sigma(perpendicular toc) and Seebeck coefficient alpha(cperpendicular toDeltaT) over the temperature range 90 - 420 K. It was found that Pb impurities in Bi2Te3 behave as acceptors; some (40%) of the incorporated Pb atoms are electrically inactive. This effect is explained by the model of crystal lattice defects based on the assumption that the Pb atoms interact with native defects in the crystal lattice of undoped Bi2Te3, that is with antisite defects Bi-Te' and vacancies V-Te(..) in the Te sublattice.