Methods of the Alignment-Relay Technique for Nanosystems: Optimization and Innovation

ISBN-13: 9783030844127 / Angielski / Twarda / 2021 / 292 str.

Monika Snowdon

Spis treści

Table of Contents

Examining Committee Membership ....................................................................................................... ii

Author's Declaration .............................................................................................................................. iii

Statement of Contributions .................................................................................................................... iv

Abstract .................................................................................................................................................. v

Résumé ................................................................................................................................................. vii

Acknowledgements ............................................................................................................................. viii

Dedication ............................................................................................................................................. ix

List of Figures ..................................................................................................................................... xiv

List of Tables ..................................................................................................................................... xxiv

List of Equations ............................................................................................................................... xxvi

List of Schemes ................................................................................................................................ xxvii

List of Abbreviations ....................................................................................................................... xxviii

Land Acknowledgement .................................................................................................................... xxxi

Tribute to Nanotubes ........................................................................................................................ xxxii

Chapter 1 : Introduction.......................................................................................................................... 1

: Background and Literature Review ............................................................................................ 3

Primer on Carbon Nanotubes ................................................................................................ 3

Fabricating Carbon Nanotubes ............................................................................................ 10

Carbon Nanotube Defects .................................................................................................... 19

Carbon Nanotube Electronic Properties .............................................................................. 21

Carbon Nanotubes as Transistors ........................................................................................ 27

Carbon Nanotube Sorting .................................................................................................... 33

Carbon Nanotube Alignment ............................................................................................... 36

Carbon Nanotube Alignment and Sorting ........................................................................... 41

Alignment Relay Technique ....................................................................................................... 44

Intermolecular Interactions with SWNTs ............................................................................ 44

Substrate Binding ................................................................................................................ 47

Surface Oxidation and Cleaning .......................................................................................... 49

Liquid Crystal Technology .................................................................................................. 51

Synthesis of the CNT Tweezer in ART ............................................................................... 54

ART Process ........................................................................................................................ 55

xi

Characterization methods ........................................................................................................... 58

Atomic Force Microscopy ................................................................................................... 58

Scanning Electron Microscopy ............................................................................................ 61

IR and Raman Spectroscopy ............................................................................................... 64

I-V Testing........................................................................................................................... 71

Additional Techniques ......................................................................................................... 77

Concluding Remarks .................................................................................................................. 80

Chapter 2 : Modifications to the ART Procedure ................................................................................. 81

Post-Carbon Nanotube Deposition: Sonication .......................................................................... 81

Results and Discussion ........................................................................................................ 82

Summary of Sonication Experiments ................................................................................ 116

Post-Carbon Nanotube Deposition: Layer-by-Layer (LBL) treatment .................................... 118

Results and Discussion ...................................................................................................... 118

Langmuir-Blodgett Attempt .............................................................................................. 121

Summary ........................................................................................................................... 122

Pre-Carbon Nanotube Deposition: Filler Molecules ................................................................ 123

Concept and Experiment ................................................................................................... 123

Results and Discussion ...................................................................................................... 124

Summary of Filler Molecule Experiments on SiO2 ........................................................... 129

Chapter 3 : Different Anchoring Group and Substrate Surfaces ........................................................ 131

Alumina coated surface ............................................................................................................ 131

Substituting a Carboxylic Acid as an Anchoring group .................................................... 133

Substituting 5CB for 8CB ................................................................................................. 138

Filler Exploration............................................................................................................... 140

α-Al2O3 (Sapphire) ............................................................................................................ 144

Au coated surface ..................................................................................................................... 147

Sulfur Anchoring Component for Au ................................................................................ 149

Gold with Filler Molecules Adaptation ............................................................................. 151

Further Directions for Sulfur in ART ................................................................................ 155

SiNX, TiO2 and using UV-Ozone cleaning ............................................................................... 156

Summary of Different Anchoring Groups and Substrate Surface Investigations .............. 159

Chapter 4 : Other nanosystems probed for alignment ........................................................................ 160

Hydrophilic Carboxylic-acid functionalized SWNTs .............................................................. 160

xii

Analysis of 78% purity SWNTs ........................................................................................ 161

Synthesis of SWNTs-COOH ............................................................................................. 163

Results and Discussion for SWNTs-COOH ...................................................................... 164

Summary of SWNTs-COOH studies ................................................................................. 169

Longer SWNTs ......................................................................................................................... 171

Smaller Diameter SWNTs ........................................................................................................ 173

Multi-Walled Carbon Nanotubes ............................................................................................. 174

Graphene Nano-Ribbons .......................................................................................................... 181

Nanowires ................................................................................................................................. 183

Graphene and Graphene Quantum Dots ................................................................................... 185

Summary of ART for Other Nanosystems ............................................................................... 186

Chapter 5 : Applying ART toward SWNTs device fabrication .......................................................... 187

Device Fabrication ................................................................................................................... 187

Optimization of LED lithography...................................................................................... 187

E-beam lithography ........................................................................................................... 191

Device Testing .......................................................................................................................... 192

Annealing Tests ................................................................................................................. 193

Bottom Gate Devices ......................................................................................................... 200

Top Gate Devices .............................................................................................................. 207

Ionic Gel Gate.................................................................................................................... 214

Substitution of Metal Electrodes ....................................................................................... 216

Additional Imaging ................................................................................................................... 217

TEM of CNTFETs ............................................................................................................. 217

Interesting Patterning Observation .................................................................................... 218

Summary .................................................................................................................................. 220

Chapter 6 : Concluding Remarks & Future Directions ...................................................................... 221

Chapter 7 : Experimental .................................................................................................................... 226

Sample Preparation for the Alignment Relay Technique ......................................................... 226

Sonication Experiments ............................................................................................................ 229

Application of Fillers ................................................................................................................ 229

SWNTs-COOH synthesis and surfactant free treatment .......................................................... 229

Langmuir Blodgett- ART combination .................................................................................... 230

Other Nanostructures for Alignment with ART: NWs, GNRs, and MWNTs .......................... 230

xiii

Characterization of ART substrates .......................................................................................... 231

Atomic Force Microscopy ................................................................................................. 231

Scanning electron microscopy ........................................................................................... 232

X-Ray Photoelectron Spectroscopy ................................................................................... 232

UV-vis spectroscopy ......................................................................................................... 232

Ellipsometry ...................................................................................................................... 233

Raman Spectroscopy ......................................................................................................... 233

Alignment Data Analysis .................................................................................................. 235

Synthesis ................................................................................................................................... 236

Attempted yet unsuccessful molecular synthesis .............................................................. 250

Field-effect Transistor Fabrication and Testing ....................................................................... 251

LED Photolithography Patterning ..................................................................................... 251

Electron Beam Lithography Patterning ............................................................................. 252

Metal Deposition ............................................................................................................... 254

Electrical Testing ............................................................................................................... 254

Probe-test ........................................................................................................................... 254

Copyright Permissions ....................................................................................................................... 256

References .......................................................................................................................................... 257

Appendix: Supplemental Data ............................................................................................................ 274

Appendix Chapter 2 ........................................................................................................................ 274

Sonication Experiments .............................................................................................................. 274

LBL and LB Experiments .......................................................................................................... 286

Filler Experiments ...................................................................................................................... 289

Appendix Chapter 3 ........................................................................................................................ 291

Appendix Chapter 4 ........................................................................................................................ 300

SWNTs-COOH .......................................................................................................................... 300

Longer length SWNTs ................................................................................................................ 312

Smaller diameter SWNTs ........................................................................................................... 313

Bottom-up synthesized GNRs Raman ........................................................................................ 317

MWNTs ...................................................................................................................................... 318

Graphene .................................................................................................................................... 318

Appendix Chapter 5 ........................................................................................................................ 319

Appendix Chapter 6 ........................................................................................................................ 331

O autorze

Monika obtained her doctorate in chemistry from the University of Waterloo, Canada. Part of her doctoral research was pursued in Japan at the soft materials chemistry group under the supervision of Dr. Dai-Ming Tang at the National Institute for Material Science. She holds a MSc in organosulfur synthesis and a BSc in nanoscience from the University of Guelph, Canada. Currently, she is a postdoctoral researcher in mechanical engineering at Dr. Zhou's lab as part of the Center for Advanced Materials Joining, University of Waterloo, and a lead product developer with Elizion Tech.

Blurb

This thesis addresses the problem of improving the alignment of carbon nanotubes (CNTs) in transistor applications, taking a unique approach using iptycenes acting as molecular tweezers in combination with a liquid crystal solvent. As part of a project to test the effectiveness of a multi-step method, the so-called Alignment Relay Technique (ART), this work contributed evidence for the selectivity and stability of ART, as well as providing the first proof-of-concept that ART can be used to create CNT field-effect transistors (FETs). The thesis effectively explains and illustrates the chemical synthesis of the tweezers, the concept and actualization of the technique, the various factors observed to influence deposition and selectivity, along with material fabrication using both photolithography and electron beam lithography. This research advances knowledge of transistors and expands the applications of small organic molecules in the field of materials science. Particular highlights of this thesis include: an extensive review of ART, its advantages, and limitations; development of new material chemistry methods for the optimization of semiconducting CNT selectivity; and a comprehensive exploration of fabrication and characterization of CNTFETs for future applications.