Bi2-xInxSe3crystals; optical properties and transport coefficients

Single crystals of Bi2-xInxSe3 (x = 0.0-0.66) were prepared from the elements of 5N purity using the modified Bridgman method. On the samples with a various content of incorporated In-atoms the reflectivity in IR-region and the transport coefficients (electrical conductivity σ⊥, Hall coefficient RH (B ∥ c), Seebeck coefficient S⊥) were measured. The results showed that the In-atoms incorporation to the crystal lattice of Bi2Se3 in the region of small concentrations of In-atoms increases the free carriers concentration, in the region of higher concentrations of In-atoms the free carriers concentration is suppressed. On the ground of measured changes in the values of transport coefficients and optical parameters (determined from the interpretation of infrared reflectivity) a model of point defects in the Bi2-x Inx Se3 crystal lattice has been suggested. This model takes into account the existence of antisite defects Bi'Se in the Bi2Se3 crystal lattice the concentration of which is suppressed by incorporated In-atoms. The built-in In-atoms form uncharged defects InxBi which are positively polarized.