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Документ Effect of deviation from stoichiometry on transport and mechanical properties of Bi2Se3 polycrystals(AIP Publishing, 2021) Menshikova, S. I.; Rogacheva, E. I.The dependences of electrical conductivity, the Hall coefficient, the Seebeck coefficient, thermoelectric power factor and microhardness of Bi2Se3 polycrystals on the degree of deviation from stoichiometry 59.9–60.0 at. % Se and temperature (77–300 K) were obtained. The samples exhibited n-type conductivity in the studied ranges of compositions and temperatures. The boundaries of the Bi2Se3 homogeneity region were estimated. A non-monotonic behavior of the concentration dependences of the properties in the studied composition range, associated with a change in the phase composition and defect structure under the deviation from stoichiometry, was observed. The calculation of the power coefficient in the temperature dependence of electron mobility showed that in a stoichiometric Bi2Se3, electrons are predominantly scattered by acoustic phonons, and under the deviation from stoichiometry the contribution of impurity scattering increases. Based on the experimental data, the Fermi energy EF was calculated in the approximation of the relaxation time and within the framework of the single-band model with a quadratic dispersion law. The obtained values of EF showed that both in stoichiometric and non- stoichiometric Bi2Se3, the conduction is mainly due to electrons in the lower conduction subband.Документ Electrical conductivity and Hall mobility of Bi2Se3 thin films with different thicknesses(Publishing House "UKRPOL" Ltd, 2018) Menshikova, S. I.; Rogacheva, E. I.Документ Quantum oscillations in thickness dependences of transport properties of topological insulator Bi2Se3 thin films(Publishing House SME "Burlaka", 2017) Rogacheva, E. I.; Sipatov, A. Yu.; Menshikova, S. I.Документ Size effects in thin PbTe films(Прикарпатський національний університет імені Василя Стефаника, 2017) Menshikova, S. I.; Rogacheva, E. I.Публікація Size Effects in Transport Properties of PbSe Thin Films(IOP Publishing Ltd, 2016) Rogacheva, E. I.; Nashchekina, O. N.; Menshikova, S. I.Публікація Thickness-dependent quantum oscillations of the transport properties in bismuth selenide thin films(Elsevier, 2019) Rogacheva, E. I.; Menshikova, S. I.; Sipatov, A. Yu.; Nashchekina, O. N.The objects of the present study were thin n-Bi2Se3 films with thicknesses d = 10–100 nm, grown by thermal evaporation of n-Bi2Se3 crystals in vacuum onto heated glass substrates. The room temperature d-dependences of the Seebeck coefficient, the Hall coefficient, and the electrical conductivity of the films exhibited an oscillatory behavior, which we attribute to quantum size effects. Such interpretation of the results is supported by the fact that experimentally determined values of the oscillation period are in quite good agreement with the theoretically calculated ones. We suggest that the large amplitude and undamped character of the oscillations in the studied range of thicknesses are connected with the topologically protected gapless surface states of Bi2Se3. The observed oscillatory character of the d-dependences of the transport coefficients should be taken into account when 2D-structures are applied in nanothermoelectricity and other fields of nanoscience and nanotechnology.