Variation of thermoelectric properties along the growth direction of n-type 90% Bi2Te3-10%Bi2Se3 single crystals grown by the zone melting method

摘要

CdI2 and CdCl2 doped n-type 90% Bi2Te3-10%Bi2Se3 single crystals were grown by the vertical zone meltingmethod, and the thermoelectric properties along the ingot wereanalyzed. The sharp increase of the Seebeck coefficient andelectrical resistivity at the last-to-freeze region were considered asa result of the evaporation of I and Cl from the molten zone. Themaximum Figure-of-Merit of the CdI2 and CdCl2 doped n-type90% Bi2Te3-10% Bi2Se3 single crystals were 2.7×10 –3/K and2.8×10 –3/K, respectively. The higher Figure-of-merit for theCdCl2 doped specimens was mainly due to the lower (k-kel). Theoptimum doping amount of CdI2 and CdCl2 for n-type 90%Bi2Te3-10% Bi2Se3 single crystals, grown by the vertical zonemelting method, were 0.075~0.10 wt% and 0.04~0.05 wt%, respectively.