Low Temperature Physics: 47, 134 (2021); https://doi.org/10.1063/10.0003175
Fizika Nizkikh Temperatur: Volume 47, Number 2 (February 2021), p. 151-158    ( to contents , go back )

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

S. I. Menshikova and Е. I. Rogacheva

National Technical University “Kharkiv Polytechnic Institute”, Kharkiv 61002, Ukraine
E-mail: olhovskaya.sveta@gmail.com
rogacheva@kpi.kharkov.ua

pos Анотація:1514

Received August 20, 2020, published online December 2 5, 2020

Abstract

The dependences of electrical conductivity, the Hall coefficient, the Seebeck coefficient, thermoelectric powerfactor and microhardness of Bi2Se3 polycrystals on the degree of deviation from stoichiometry 59.9–60.0 at. % Seand 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-bandmodel 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.

Key words: bismuth selenide, stoichiometry, transport properties, defect structure.

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