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Registration Number

0221U103762, 0118U002043 , R & D reports

Title

The influence of size effects on the thermoelectric properties of thin-film nanostructures based on solid solutions of topological insulators of different types

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Head

Rogachova Olena I., Доктор фізико-математичних наук

Registration Date

25-02-2021

Organization

National Technical University "Kharkiv Polytechnic Institute"

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 The research objects are classical and quantum size effects in thin film nanostructures based on topological insulators - V2VI3, IV-VI, Bi1-xSbx thermoelectrics, and the effect of topological surface states and structural disordering on the manifestation of size effects and thermoelectric properties. The research purpose is to detect size effects in thin film nanostructures based on topological insulators - V2VI3, IV-VI and Bi1-xSbx, and to identify the specificity of their manifestation associated with the presence of the metallic surface layer with a Dirac dispersion law, to establish the influence of size effects and structure disordering on thermoelectric properties. The research methods include measurements of electrical conductivity, the Seebeck coefficient, the Hall coefficient, and magnetoresistance in the temperature ranges of 77 - 300 К and in the magnetic field range of 0 - 1 T. The dependences of thermoelectric and galvanomagnetic properties on temperature, magnetic field, composition and thickness of thin V2VI3, IV-VI, і Bi1-xSbx films grown on glass substrates by thermal evaporation in vacuum using polycrystalline samples, prepared and characterized during the first stage of this project, as initial materials, were studied. Effect of aging on thermoelectric properties of Bi2Te3 crystals and thin films was studied. Classical and quantum size effects were observed. An oscillatory behavior of the thickness dependences of thermoelectric properties for thin films was detected and attributed to the manifestation of quantum size effects. The oscillation period theoretically calculated for an infinitely deep quantum well was in good agreement with the experimental results. The influence of topological surface states with the Dirac dispersion law on the manifestation of size effects in thin Bi2Se3 і Bi2(Te1-xSex)3 films was established. The effect of anion substitution in V2VI3 compounds on size quantization of energy spectrum was identified

Product Description

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Doroshenko Hanna M
Menshykova Svitlana I
Nashchekina Olha M
Rogachova Olena I
Khramova Tatyana I
Shelest Tatyana M

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2021-02-25