Positiverole of Sn impurity on thermoelectric properties of Bi2Te3-based singlecrystals


M.K. Zhitinskaya1, S. A. Nemov1, M.Yu. Nikulina1,T. E. Svechnikova2, E. Müller3


1StatePolitechnical University, St-Petersburg

2BaikovInstitute of Metallurgy and Materials Sciences, Moscow

3GermanAerospace Center (DLR), Institute of Materials Research, D-51170 Köln, Germany


An experimental studyon the influence of Sn doping on the thermal conductivity of Bi2Te3and Bi2Te3 with Te partially replaced by Se isreported. The thermoelectric properties: (thermal and electrical conductivity,Seebeck coefficient and its spatial distribution on the sample surface) of Bi2Te3-basedsingle crystals have been determined. The crystals were grown by Czochralskitechnique. The composition of samples is given by the chemical formula Bi2-xSnxTe3-ySey.

Analysis of thermalconductivity has shown that the lattice thermal resistivity Wl is changing withthe amount of Sn impurity and with the type of an additional impurity. Thisfact is linked to the interaction of Sn impurity atoms with intrinsic defects.It was found that the maximum of Wl corresponds to a concentration of tin atomscSn ~ (0.2 - 0.4) at%.

An increase by Snaddition of the homogeneity of the spatial concentration distribution wasdetected by measurements of the local Seebeck coefficient by a scanningthermo-probe.

The obtainedexperimental data support to the interpretation that the incorporation of Snatoms into Bi2Te3 and into Bi2Te3-xSex is accompanied by theformation of a band of resonant Sn-states against the background of the allowedvalence-band spectrum.