Defect structure of Pb-doped Bi₂Te₃ single crystals

Abstract

Pb-doped Bi₂Te₃ single crystals with a Pb concentration of c _Pb = 0−9.4 ×  10²⁵m⁻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(B∥c), electrical conductivity σ_⊥c and Seebeck coefficient α(c⊥ΔT) 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 and vacancies in the Te sublattice.