POINT-DEFECTS IN BI2-XINXTE3 SINGLE-CRYSTALS

Single crystals of Bi2-xInxTe3 (x = 0 to 0.3) are synthesised from ele ments 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 d ecrease in the concentration of free charge carriers (holes), until in version of the conductivity type from p to n takes place at a value of x approximate to 0.1 and in samples with x > 0.1 an increase in the c oncentration of free electrons is observed. This effect is accounted f or by a model of point defects in the Bi2-xInxTe3 crystal lattice. The model is based on the idea of substitutional defects In-Bi(x) leading to a decrease of the concentration of anti-site Bi'(Te) defects and a simultaneous increase of the concentration of V-Te(..) vacancies in t he Te sublattice.