Point defects in Bi2 − xInx Te3 single crystals

Single crystals of Bi2 − xInxTe3 (x = 0 to 0.3) are synthesised from elements of semiconductor purity using a modified Bridgman technique. The results of the measurements of Hall constant, electrical conductivity, and Seebeck coefficient show that increasing value of x leads to a decrease in the concentration of free charge carriers (holes), until inversion of the conductivity type from p to n takes place at a value of x ≈︁ 0.1 and in samples with x > 0.1 an increase in the concentration of free electrons is observed. This effect is accounted for by a model of point defects in the Bi2 − xInxTe3 crystal lattice. The model is based on the idea of substitutional defects In leading to a decrease of the concentration of anti-site Bi defects and a simultaneous increase of the concentration of V Te ¨︂ vacancies in the Te sublattice.