Doping of the Bi1.9Sb0.1Te3 solid solution with Sn impurity

Abstract

In (Bi1.9Sb0.1)1 − x Sn x Te3 solid solution with different contents of Sn, the electrical conductivity (σ11) and the Hall (R 123 and R 321), Seebeck (S 11 and S 33), and Nernst-Ettingshausen (Q 123 and Q 321) coefficients have been measured. It is shown that doping with tin strongly modifies temperature dependences of the kinetic coefficients. The effect of tin on electrical homogeneity of the samples has been studied: with increasing number of Sn atoms embedded, crystals become more homogeneous. These features indicate the presence of the quasi-local states of Sn in the valence band of Bi1.9Sb0.1Te3. Within a one-band model, we estimated the effective mass of the density of hole states (m d ), the energy gap extrapolated to 0 K (E g0 = 0.20–0.25 eV), the energy of impurity states (E Sn ≈ 40–45 meV), and the scattering parameter (r ≈ 0.1–0.4). Numerical values of the scattering parameter indicate a mixed mechanism of scattering in the samples under investigation with dominant scattering at acoustic phonons. With increasing content of tin in the samples, the contribution of impurity scattering increases.