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Identifier 000430439
Title Electronic and optical properties of ZnX (X:S,Se,Te) and MnxZnyNiyO4 : a first principles investigation
Alternative Title Ηλεκτρονικές και οπτικές ιδιότητες των ZnX (X:S,Se,Te) και MnxZnyNiO4
Author Περβολαράκης, Εμμανουήλ
Thesis advisor Ρεμεδιάκης, Ιωάννης
Reviewer Κοπιδάκης, Γεώργιος
Στούμπος, Κωνσταντίνος
Abstract Zinc is a common material that is often used in modern materials due to its abundance,low price, non-toxicity, material stability and its great ability to alloy with most metallicelements. Zinc-containing oxides and chalcogenides are used extensively in a variety ofapplications. In this thesis, we consider two characteristic families of Zn-based materials:Zn chalcogenides and Zn-doped Mn2NiO4.The Zn-chalcogenide family of materials (ZnS, ZnSe, ZnTe) are direct gap II-VI semicon-ductors which are excellent base materials for optical device technology due to their largegap and optical properties. Mn2NiO4, on the other hand, is a well-known material as atemperature sensor thanks to its negative temperature coefficient of resistance (NTCR)but its alloys with Zn require further investigation. In this thesis, we employ densityfunctional theory (DFT) in the Projector-Augmented Wave (PAW) implementation tocalculate the electronic structure and characteristic properties of these materials.In the first part of the thesis we probe the structural, electronic and optical properties ofthe Zn chalcogenide family of materials using first principles calculations. Even thoughDFT can produce really accurate results for the ground state, it falls short when itcomes to excited state properties like the semiconductor band-gap and the absorptionspectrum. For a more accurate description, we solve the Bethe-Salpeter Equation in theGW approximation in order to include many-body effects in our calculations that arisefrom the electron-hole interactions like excitons.The second part of this thesis revolves around Mn2NiO4and its alloying by the Zn sub-stitution of Mn. We calculate the ground state structure, magnetization and density ofstates of these materials for various concentrations Zn. We then proceed to calculatethe properties of two similar material series of the MnxZnyNizO4type. Although thesealloys have very promising electronic properties, detailed simulations as well as experi-ments are missing. In close collaboration with experimental colleagues, we will unravelthe potential of these materials for sensing applications.
Language English
Issue date 2020-07-31
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Materials Science and Technology--Post-graduate theses
  Type of Work
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