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Identifier 000460082
Title Theoretical study of two-dimensional nanostructures
Alternative Title Θεωρητική μελέτη δισδιάστατων νανοδομών
Author Βαϊλάκης, Γεώργιος
Thesis advisor Κοπιδάκης, Γεώργιος
Reviewer Ρεμεδιάκης, Ιωάννης
Παπάζογλου, Δημήτριος
Αρματάς, Γεράσιμος
Κιοσέογλου, Γεώργιος
Λάππας, Αλέξανδρος
Λέκκα, Χριστίνα
Abstract In this work, we perform density functional theory (DFT) calculations for the atomic and electronic structure of defected Two-dimensional (2D) nanostructures, heterostructures consisting of combinations of Transition Metal Dichalcogenide (TMD) monolayers (MLs), Graphene (Gr), and other materials. Due to the large size of the simulation cells required, DFT calculations are very demanding and the results need careful interpretation using non-trivial computational tools. We present in detail the methods we develop for the construction of optimized simulation cells and for unfolding the electronic band structures from their Brillouin Zone (BZ). The effective band structure (EBS) produced allows for a clear and direct comparison between electronic properties of 2D defected nanostructures and heterostructures with their pristine or constituent MLs. Applying our methodology to Gr/TMD and TMD/TMD heterostructures, several experimental observations are explained and predictions are made. Our methodology also proves very useful in investigating defects and adsorption on 2D MLs. In conjunction with experiments, our DFT calculations show how n-doped WSe2 ML becomes a p-doped semiconductor via photochlorination. In another synergy with experiment, our DFT calculations show that Fe-vacancies in Fe2Se2 MLs give rise to a stretched lattice at a relatively low energy cost. Finally, we present our theoretical results for hydrogen adsorption on CuCo2S4/Ni2P heterostructure within another collaboration with experimentalists. Our DFT-based studies with the methodology we developed for building simulations and interpreting electronic band structures, combined with data from experiments, besides explaining observed phenomena, provide a general framework for making predictions which should be useful in future experiments and applications.
Language English
Subject Band structure unfolding
Transition metal dichalcogenides
Van der waals heterostructures
Van der waals ετεροδομές
Δισδιάστατα υλικά
Διχαλκογενίδια μετάλλων μετάπτωσης
Ξεδίπλωμα δομής ενεργειακών ζωνών
Issue date 2023-11-29
Collection   School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/9/b/6/metadata-dlib-1698924147-645962-17731.tkl Bookmark and Share
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