Properties of Sb/sub 2/Te/sub 3/ single crystals doped with tin, selenium, bismuth

Electrophysical properties (Seebeck coefficient, electro- and thermoconductivities, Hall coefficient and Hall mobility) of Sb/sub 2/Te/sub 3/ single crystals, doped with tin up to 1 mass.%, selenium up to and bismuth up to 7 mass.% in various crystallographic directions were studied. The single crystals were grown using Czochralski technique with the melt supply through a floating crucible. Using atomic absorption analysis were determined the effective distribution coefficients of the tin and of the selenium in Sb/sub 2/Te/sub 3/. The concentration dependencies of electrophysical properties of doped crystals were studied. It was established that tin atoms act as acceptors and one atom of Sn gave 1.7 holes. Doping of selenium and bismuth decrease deviation from stoichiometric composition of Sb/sub 2/Te/sub 3/. The possible mechanisms of the incorporation of Sn, Se and Bi atoms into the crystal lattice of Sb/sub 2/Te/sub 3/ were discussed. At room temperature for the whole crystals the anisotropy of electro- and thermoconductivities was highest between the directions parallel and perpendicular of basal planes (2-4). Anisotropy factors of Seebeck coefficient were 0.8-0.9. The temperature dependencies of electroconductivity and Seebeck coefficient in directions parallel and perpendicular of basal planes of the crystals doped with tin in range 100-300 K were studied.