Browsing by Author "Apte, Amey Anant"

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    Investigating Low Temperature Optical Properties and Structural Phase Transformation in 2D MoWSe2 Alloys
    (2018-04-17) Apte, Amey Anant; Ajayan, Pulickel M
    Two-dimensional materials have been increasingly investigated over the last decade for their ease of exfoliation from van der Waals’ solids and the drastic change in properties when they transition from bulk to monolayer thickness. Transition metal dichalcogenides (TMDCs) are a prominent class of such materials whose prototypical monolayers have been shown to exhibit various stacking phases, electronic and optical properties, mechanical strength, improved catalytic activity, etc. Equally interesting albeit not so exhaustively explored are alloys of such 2D TMDC materials. This work focuses on monolayer molybdenum tungsten diselenide (Mo1-xWxSe2) alloy. The general properties of single phase TMDC materials are discussed, followed by alloys and their synthesis and investigation of their properties. Finally, two experiments are discussed: the photoluminescence of 2D Mo1-xWxSe2 at low temperatures and the strain induced in-situ structural phase transformation of the alloy.
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    Investigation Into The Synthesis And Characterization Of Two-dimensional Molybdenum-based Dichalcogenide Alloys and Oxides And Their Properties
    (2019-07-29) Apte, Amey Anant; Ajayan, Pulickel M
    Two-dimensional materials have been proposed as the basis of a number of upcoming applications due to their exciting electronic, optical, mechanical, and physico-chemical properties. This was experimentally demonstrated in the case of graphene, and followed by transition metal dichalcogenides (TMDCs), atomically flat sheets whose two-dimensional forms impart great flexibility along with a range of electronic band-structures. However, unlike graphene, TMDCs boast of a variety of atomic combinations due to an assortment of transition metals and chalcogens. The first part of this thesis builds upon the previous thesis work of exploring the space of multi-component TMDC alloys by doping at both cation and anion sites via different methods of chemical vapor deposition. Various doping levels are explored and characterized to detect structural phase transformations and the rise of emergent properties. Further, the thermodynamic nature of alloy vs heterostructure formation in cation-doped TMDC system is explored for the first time. The second part of the thesis explores novel elemental and compound ultra-thin materials and their properties and their uniqueness in the ever-growing library of two dimensional materials.