Effect of deviation from stoichiometry on transport and mechanical properties of Bi2Se3 polycrystals

The dependences of electrical conductivity, the Hall coefficient, Seebeck thermoelectric power factor and microhardness Bi2Se3 polycrystals on degree deviation from stoichiometry 59.9–60.0 at. % Se temperature (77–300 K) were obtained. samples exhibited n-type conductivity in studied ranges compositions temperatures. boundaries homogeneity region estimated. A non-monotonic behavior concentration properties composition range, associated with a change phase defect structure under stoichiometry, was observed. calculation coefficient dependence electron mobility showed that stoichiometric Bi2Se3, electrons are predominantly scattered by acoustic phonons, contribution impurity scattering increases. Based experimental data, Fermi energy EF calculated approximation relaxation time within framework single-band model quadratic dispersion law. obtained values both non- conduction is mainly due to lower subband.