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Title:Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit
Author(s):Wang, Cai Mike
Director of Research:Nam, SungWoo
Doctoral Committee Chair(s):Nam, SungWoo
Doctoral Committee Member(s):Saif, Taher; Murphy, Catherine J; Lyding, Joseph W; Mensing, Glennys A
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):0D/1D materials
2D materials
2.5D
3D
adaptive materials
atomic force microscopy
atomically thin
AuNPs
buckling
carbon dioxide
chemical vapour deposition
CO2
conformable materials
copper
crumpling
deformation
delamination
dichroism
electrochemistry
electrolyte
excitonics
field-effect transistor
flexible electronics
gold nanoparticles
graphene
grating
green chemistry
green manufacturing
heterostructures
interfaces
layered materials
lithography-free
low-dimensional materials
materials processing
mechanical instabilities
metamaterials
molybdenum disulphide
MoS2
nano-manufacturing
nanomaterials
nanoparticles
nanoscale patterning
nano-templating
photoluminescence
plasmonics
Raman spectroscopy
self-assembly
semiconductors
strain
surface instabilities
surface wrinkling
sustainable manufacturing
three-dimensional
transition metal chalcogenide
two-dimensional materials
van der Waals materials
Abstract:Two-dimensional (2D) layered materials, exemplified by the prototypical graphene, have been intensively studied for their diverse material properties and superlative mechanical strength. Due to their atomically-thin nature, weak basal plane van der Waals interactions, and vanishing bending stiffness, 2D materials are extremely flexible and thus susceptible to mechanical instabilities that result in deformed out-of-plane morphologies. Such unique combination of material properties and mechanical anisotropy presents new scientific and practical challenges, but also enables novel opportunities in the nanomanufacture of 2D materials and of their derivative materials systems and devices. Surface instabilities (e.g. wrinkling and buckling) and interfacial phenomena (e.g. delamination) are typically deemed as engineering nuisances and failure modes. However, these universally ubiquitous phenomena can instead be harnessed to realize novel strategies and architectures for precise manipulation and assembly of 2D and other low-dimensional nanoscale materials, the combination of which contributes to an ever-growing toolset of capabilities towards layer-by-layer nanomanufacturing at the atomically-thin limit. This dissertation details new methods that have been developed to deterministically create hierarchical and deformed 2D materials via large-scale elastic strain engineering and controlled shape memory deformation. The emergent tunable 3D architectures arising from flat 2D materials exhibit large-scale, uniform, and well-organized patterns with characteristic length scales spanning from tens of nanometers to few microns without any a priori patterning or lithographic definition of the constituent sub-nanometer 2D thin films. By controlling bulk substrate deformation, this highly robust and scalable process imparts spatially heterogeneous strain gradients that perturb the intrinsic lattice structure and consequently the local optoelectronic properties of atomically-thin monolayer graphene analogs such as semiconducting transition metal chalcogenides, thus creating highly uniform and periodic lateral superlattice configurations. In addition, the generality of this self-patterning scheme allows for facile and scalable definition of nanoscale architectures for template guided nano-convective/capillary self-assembly of arbitrary 0D/1D nanoparticles onto deformed 2D substrates. Here, high quality colloidally prepared gold nanoparticles of diverse shapes and sizes readily self-assemble into various tunable structured mixed-dimensional metamaterials, opening the opportunity to investigate emergent phenomena such as those arising from coupling between metallic plasmonic nanostructures/nanoparticles with excitons and other quasiparticles in 2D materials. Finally, with the eventual goal towards large-scale nano-manufacturing of these 2D materials and devices, a new technique has been developed to cleanly and sustainably manufacture graphene and recycle the catalyst metal substrate using benign materials. By separating the 2D material from the growth substrate via electrochemical interfacial delamination, this method forgoes the harsh chemicals typically used in conventional processing of 2D materials while simultaneously avoiding expenditure of the expensive precursors, thus leading to scalable production of high quality, clean graphene with reduced negative externalities.
Issue Date:2018-07-09
Type:Text
URI:http://hdl.handle.net/2142/101761
Rights Information:Copyright 2018 Michael Cai Wang
Date Available in IDEALS:2018-09-27
Date Deposited:2018-08


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