Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/126074
Title: STRUCTURAL AND CHEMICAL MODIFICATIONS OF TWO-DIMENSIONAL TRANSITION METAL DICHALCOGENIDES
Authors: AMARA KIRAN KUMAR
Keywords: Layered, transition metal, dichalcogenides, phase transformation, structural evolution, chemical thinning.
Issue Date: 21-Jan-2016
Abstract: Layered transition metal dichalcogenides (LTMDs) are a family of materials sharing van der Waals layer structures and is effectively two-dimensional (2D) in morphology. We have investigated correlations between the chemical reactivity of LTMDs such as MoS2 and WS2 and their atomic and electronic structure using reducing reagents such as n-BuLi and LiBH4 with the help of Raman spectroscopy and transmission electron microscopy. We report in-situ observation of dynamic structural evolution of one-dimensional bonding network in single layer WS2 induced by electron beam irradiation. Our first principles calculations indicate that this dynamic structural evolution is a response to local electronic instabilities that weaken the W-S bonds in the bonding network. We also report on the preparation of mono- and bi-layer MoS2 from a bulk crystal by facile chemical etching with concentrated nitric acid (HNO3). The flakes obtained by chemical etching exhibit electronic quality comparable to that of mechanically exfoliated counterparts.
URI: http://scholarbank.nus.edu.sg/handle/10635/126074
Appears in Collections:Ph.D Theses (Open)

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