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Engineering The Electronic Structure Of Atomically Precise Graphene Nanoribbons
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Book Synopsis Engineering the Electronic Structure of Atomically-precise Graphene Nanoribbons by : Giang Duc Nguyen
Download or read book Engineering the Electronic Structure of Atomically-precise Graphene Nanoribbons written by Giang Duc Nguyen and published by . This book was released on 2006 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene nanoribbons (GNRs) have recently attracted great interest because of their novel electronic and magnetic properties, as well as their significant potential for device applications. Although several top-down techniques exist for fabricating GNRs, only bottom-up synthesis of GNRs from molecular precursors yields nanoribbons with atomic-scale structural control. Furthermore, precise incorporation of dopant species into GNRs, which is possible with bottom-up synthesis, is a potentially powerful way to control the electronic structure of GNRs. However, it is not well understood how these dopants affect the electronic structure of GNRs. Are these effects dependent on the dopant site? Can the band gap be tuned by doping? This dissertation helps to answer these questions through studying the electronic structure of bottom-up grown GNRs with controlled atomic dopants. The effects of edge and interior doping with different atomic species such as sulfur, boron and ketone were investigated and showed significant site dependence. Topographic and local electronic structure characterization was performed via scanning tunneling microscopy & spectroscopy (STM & STS) and compared to first-principle calculations. The chemical structure of GNRs and GNR heterojunctions was characterized by CO-tip-functionalized non-contact atomic force microscopy (nc-AFM) as well as by a newly developed technique of bond-resolved STM (BRSTM). In an effort to develop a new method for directly synthesizing GNRs on an insulating substrate, we also studied light-induced photo-isomerization of azobenzene molecules adsorbed on an insulating surface of CVD-grown monolayer boron nitride (BN) on Cu(111). This study provides important insights into molecular behavior on an insulating surface, how to couple light to an STM system, and how to utilize local field enhancement effects due to surface plasmon resonance.
Book Synopsis Electronic Properties of Atomically Precise Graphene Nanoribbons by :
Download or read book Electronic Properties of Atomically Precise Graphene Nanoribbons written by and published by . This book was released on 2015 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Structure- and Adatom-Enriched Essential Properties of Graphene Nanoribbons by : Shih-Yang Lin
Download or read book Structure- and Adatom-Enriched Essential Properties of Graphene Nanoribbons written by Shih-Yang Lin and published by CRC Press. This book was released on 2018-11-19 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structure- and Adatom-Enriched Essential Properties of Graphene Nanoribbons offers a systematic review of the feature-rich essential properties in emergent graphene nanoribbons, covering mainstream theoretical and experimental research. It includes a wide range of 1D systems; namely, armchair and zigzag graphene nanoribbons with and without hydrogen terminations, curved and zipped graphene nanoribbons, folded graphene nanoribbons, carbon nanoscrolls, bilayer graphene nanoribbons, edge-decorated graphene nanoribbons, and alkali-, halogen-, Al-, Ti, and Bi-absorbed graphene nanoribbons. Both multiorbital chemical bondings and spin arrangements, which are responsible for the diverse phenomena, are explored in detail. First-principles calculations are developed to thoroughly describe the physical, chemical, and material phenomena and concise images explain the fundamental properties. This book examines in detail the application and theory of graphene nanoribbons, offering a new perspective on up-to-date mainstream theoretical and experimental research.
Book Synopsis Introduction to Graphene-Based Nanomaterials by : Luis E. F. Foa Torres
Download or read book Introduction to Graphene-Based Nanomaterials written by Luis E. F. Foa Torres and published by Cambridge University Press. This book was released on 2014-01-23 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed primer describing the most effective theoretical and computational methods and tools for simulating graphene-based systems.
Book Synopsis Graphene Science Handbook by : Mahmood Aliofkhazraei
Download or read book Graphene Science Handbook written by Mahmood Aliofkhazraei and published by CRC Press. This book was released on 2016-04-21 with total page 592 pages. Available in PDF, EPUB and Kindle. Book excerpt: Examines the Low Resistivity, High Mobility, and Zero Bandgap of GrapheneThe Graphene Science Handbook is a six-volume set that describes graphene's special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovoltaic
Book Synopsis Physics and Chemistry of Graphene by : Toshiaki Enoki
Download or read book Physics and Chemistry of Graphene written by Toshiaki Enoki and published by CRC Press. This book was released on 2013-01-24 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a chemistry aspect, graphene is the extrapolated extreme of condensed polycyclic hydrocarbon molecules to infinite size. Here, the concept on aromaticity which organic chemists utilize is applicable. Interesting issues appearing between physics and chemistry are pronounced in nano-sized graphene (nanographene), as we recognize the importance o
Download or read book Graphene Chemistry written by De-en Jiang and published by John Wiley & Sons. This book was released on 2013-10-14 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: What are the chemical aspects of graphene as a novel 2D material and how do they relate to the molecular structure? This book addresses these important questions from a theoretical and computational standpoint. Graphene Chemistry: Theoretical Perspectives presents recent exciting developments to correlate graphene’s properties and functions to its structure through state-of-the-art computational studies. This book focuses on the chemistry aspect of the structure-property relationship for many fascinating derivatives of graphene; various properties such as electronic structure, magnetism, and chemical reactivity, as well as potential applications in energy storage, catalysis, and nanoelectronics are covered. The book also includes two chapters with significant experimental portions, demonstrating how deep insights can be obtained by joint experimental and theoretical efforts. Topics covered include: Graphene ribbons: Edges, magnetism, preparation from unzipping, and electronic transport Nanographenes: Properties, reactivity, and synthesis Clar sextet rule in nanographene and graphene nanoribbons Porous graphene, nanomeshes, and graphene-based architecture and assemblies Doped graphene: Theory, synthesis, characterization and applications Mechanisms of graphene growth in chemical vapor deposition Surface adsorption and functionalization of graphene Conversion between graphene and graphene oxide Applications in gas separation, hydrogen storage, and catalysis Graphene Chemistry: Theoretical Perspectives provides a useful overview for computational and theoretical chemists who are active in this field and those who have not studied graphene before. It is also a valuable resource for experimentalist scientists working on graphene and related materials, who will benefit from many concepts and properties discussed here.
Book Synopsis Physics and Chemistry of Graphene (Second Edition) by : Toshiaki Enoki
Download or read book Physics and Chemistry of Graphene (Second Edition) written by Toshiaki Enoki and published by CRC Press. This book was released on 2019-11-01 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene has been attracting growing attentions in physics, chemistry, and device applications after the discovery of micromechanically cleaved graphene sheet by A. Geim and K. Novoselov, who were awarded the 2010 Nobel Prize in Physics. The electronic structure of graphene, which is described in terms of massless Dirac fermions, brings about unconventional electronic properties, which are not only an important basic issue in condensed matter physics but also a promising target of cutting-edge electronics/spintronics device applications. Meanwhile, from chemistry aspect, graphene is the extreme of condensed polycyclic hydrocarbon molecules extrapolated to infinite size. Here, the concept on aromaticity, which organic chemists utilize, is applicable. Interesting issues appearing between physics and chemistry are pronounced in nanosized graphene (nanographene), as we recognize the importance of the shape of nanographene in understanding its electronic structure. This book comprehensively discusses the fundamental issues related to the electronic, magnetic, and chemical properties of condensed polycyclic hyodrocarbon molecules, nanographene, and graphene.
Book Synopsis The Rational Design and Synthesis of Graphene Nanoribbons and Graphene Nanoribbon Functional Nanoarchitectures by : Rebecca Ann Durr
Download or read book The Rational Design and Synthesis of Graphene Nanoribbons and Graphene Nanoribbon Functional Nanoarchitectures written by Rebecca Ann Durr and published by . This book was released on 2017 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene nanoribbons (GNRs) are narrow strips of graphene that have exceptional phys-ical and electronic properties. GNR band-gap engineering by fine-tuning the width, edge geometry, and doping pattern of GNRs is required for integration into post-silicon electronic devices. To this end, we have developed several techniques to create armchair and chevron GNRs of varying widths (Chapter 2). In order to further tune the electronic properties of GNRs, we explore the synthesis and applications of a series of doped GNRs (Chapter 3). Namely, incorporating N-, O-, and S-dopant atoms along the edges of chevron GNRs induces a characteristic shift in the energy of conduction and valence band edge states. Furthermore, the controlled synthesis of atomically-precise bottom-up GNR heterojunctions represents a critical step toward the goal of integrating GNRs into device applications where their ex-ceptional electronic properties can be exploited. To this end, we developed two methods of creating atomically precise GNR heterojunctions (Chapter 4), first via post-synthetic mod-ification of the GNR edges, and second by employing a hierarchical growth process. Our work demonstrates tunable methods for band-gap engineering of graphene nanostructures for advanced electronic applications.
Book Synopsis Carbon Nanotubes: Quantum Cylinders of Graphene by :
Download or read book Carbon Nanotubes: Quantum Cylinders of Graphene written by and published by Elsevier. This book was released on 2008-09-10 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is devoted to mostly to nanotubes, unique synthetic nanoscale quantum systems whose physical properties are often singular (i.e. record-setting). Nanotubes can be formed from a myriad of atomic or molecular species, the only requirement apparently being that the host material or “wall fabric be configurable as a layered or sheet-like structure. Nanotubes with sp2-bonded atoms such as carbon, or boron together with nitrogen, are the champions of extreme mechanical strength, electrical response (either highly conducting or highly insulating), and thermal conductance. Carbon nanotubes can be easily produced by a variety of synthesis techniques, and for this reason they are the most studied nanotubes, both experimentally and theoretically. Boron nitride nanotubes are much more difficult to produce and only limited experimental characterization data exist. Indeed, for boron nitride nanotubes, theory is well ahead of experiment. For these reasons this volume deals largely with carbon nanotubes. Conceptually, the "building block" for a carbon nanotube is a single sheet of graphite, called graphene. Recently, it has become possible to experimentally isolate such single sheets (either on a substrate or suspended). This capability has in turn fueled many new theoretical and experimental studies of graphene itself. It is therefore fitting that this volume contains also a chapter devoted to graphene. - Comprehension- Overview- Highlights in the field
Book Synopsis Graphene, Carbon Nanotubes, and Nanostructures by : James E. Morris
Download or read book Graphene, Carbon Nanotubes, and Nanostructures written by James E. Morris and published by CRC Press. This book was released on 2017-07-28 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene, Carbon Nanotubes, and Nanostructures: Techniques and Applications offers a comprehensive review of groundbreaking research in nanofabrication technology and explores myriad applications that this technology has enabled. The book examines the historical evolution and emerging trends of nanofabrication and supplies an analytical understanding of some of the most important underlying nanofabrication technologies, with an emphasis on graphene, carbon nanotubes (CNTs), and nanowires. Featuring contributions by experts from academia and industry around the world, this book presents cutting-edge nanofabrication research in a wide range of areas. Topics include: CNT electrodynamics and signal propagation models Electronic structure calculations of a graphene–hexagonal boron nitride interface to aid the understanding of experimental devices based on these heterostructures How a laser field would modify the electronic structure and transport response of graphene, to generate bandgaps The fabrication of transparent CNT electrodes for organic light-emitting diodes Direct graphene growth on dielectric substrates, and potential applications in electronic and spintronic devices CNTs as a promising candidate for next-generation interconnect conductors CMOS–CNT integration approaches, including the promising localized heating CNT synthesis method CNTs in electrochemical and optical biosensors The synthesis of diamondoids by pulsed laser ablation plasmas generated in supercritical fluids, and possible applications The use of DNA nanostructures in lithography CMOS-compatible silicon nanowire biosensors The use of titanium oxide-B nanowires to detect explosive vapors The properties of protective layers on silver nanoparticles for ink-jet printing Nanostructured thin-film production using microreactors A one-stop reference for professionals, researchers, and graduate students working in nanofabrication, this book will also be useful for investors who want an overview of the current nanofabrication landscape.
Book Synopsis Tailoring Electronic Structure and Properties of Graphene Using Functional Organic Molecules by :
Download or read book Tailoring Electronic Structure and Properties of Graphene Using Functional Organic Molecules written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific and technological interest in graphene has rapidly grown because of the outstanding physical and electronic properties of this two-dimensional material. To fully realize its technological potential, it is important to engineer a band gap as well as the charge carrier concentration through doping. In this thesis, we present routes to address both these aspects. Graphene is a semimetal and therefore it does not have a technologically relevant band gap. To address this problem, it has been shown that sub-20 nm patterning can be used to open up a band gap in graphene through the quantum confinement effect. We present approaches for creating semiconducting nanoperforated graphene and graphene nanoribbons using block copolymer lithography, which addresses all of the following challenges simultaneously: (i) scalability, (ii) compatibility with the current manufacturing processes, (iii) high resolution, and (iv) pattern fidelity. By developing the materials and processes for the fabrication of sub-10 nm features over large areas, we study the structure-property relationships in nanopatterned graphene as a function of constriction width. We examine the limitations of top-down etching based fabrication methods in detail by examining the edge defect structures through Raman spectroscopy and electronic transport characterizations. These studies underline the importance of edge structure engineering in combination with patterning techniques to attain high quality semiconducting graphene. In the second part of the thesis, we demonstrate a strategy to effectively control doping in graphene without degradation of the electronic properties. We do so by noncovalently latching a photoisomerizable dipolar azobenzene derivative to graphene via [pi]-[pi] interaction to create stable chromophore/graphene hybrids. A reversible molecular transformation triggered by light was used as an additional handle to reversibly modulate charge carrier concentration while retaining high mobility of pristine graphene. As the molecules switch reversibly from trans to cis upon UV light illumination, the dipole moment changes, hence the extent of doping in graphene. Through experimental and theoretical studies, we develop mechanistic insight into the observed enhancement of Raman intensity from the chromophore attached to graphene.
Book Synopsis Raman Fingerprints of Atomically Precise Graphene Nanoribbons by :
Download or read book Raman Fingerprints of Atomically Precise Graphene Nanoribbons written by and published by . This book was released on 2016 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bottom-up approaches allow the production of ultranarrow and atomically precise graphene nanoribbons (GNRs) with electronic and optical properties controlled by the specific atomic structure. Combining Raman spectroscopy and ab initio simulations, we show that GNR width, edge geometry, and functional groups all influence their Raman spectra. As a result, the low-energy spectral region below 1000 cm-1 is particularly sensitive to edge morphology and functionalization, while the D peak dispersion can be used to uniquely fingerprint the presence of GNRs and differentiates them from other sp2 carbon nanostructures.
Book Synopsis On-Surface Characterization of Atomically Precise Graphene Nanoribbons by : Jacob D. Teeter
Download or read book On-Surface Characterization of Atomically Precise Graphene Nanoribbons written by Jacob D. Teeter and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene-based materials have been the focus of intense research in recent years, and owing to the desirable properties they possess, the variety of potential applications for them is likewise impressive. Chapter 1 discusses graphene nanoribbons (GNRs) and how their precise atomic features exhibit critical influence over electronic characteristics such as band gaps, magnetic edge states, and topological phases. One can therefore engage in design of molecular precursors to build atomically precise GNRs from the bottom up with desired features which can be probed with surface science techniques. These elements include ribbon width, edge geometry, heteroatomic doping, and many more. In this dissertation are results of scanning probe microscopy experiments to examine structural and electronic characteristics of several GNR structures derived from surface-assisted synthesis techniques.First, we studied the growth of chevron GNRs on Cu(111) (Chapter 2). Epitaxial growth of chevron polymers and GNRs at low temperatures arose out of the strong interactions between structure and surface.In Chapter 3 we discuss the development of an alternative deposition technique, direct contact transfer (DCT). It arose as an analogue of dry contact transfer for solution-synthesized GNRs. The procedure was demonstrated for two precursors, and the intermediates observed in the process of annealing were determined by DFT to be stabilized by Ï0-Ï0 interactions.Chapter 4 covers the on-surface synthesis of laterally extended chevron GNRs (eGNRs). By slight modification of the chevron precursor structure, the band gap of the GNRs was reduced in accordance with established theory. In Chapter 5 results are presented on the on-surface synthesis of intrinsically porous chevron-derived GNRs. These GNRs featured electronic states at their pores as well as reduced band gaps relative to chevron GNRs.Chapter 6 details work on the growth of GNRs from a precursor with two centers of rotation and the potential for influencing its self-assembly.Finally, Chapter 7 contains a summary of the work performed as well as directions to be explored in the future as relate to this project.
Book Synopsis Electronic Structure Imperfections and Chemical Bonding at Graphene Interfaces by : Brian Joseph Schultz
Download or read book Electronic Structure Imperfections and Chemical Bonding at Graphene Interfaces written by Brian Joseph Schultz and published by . This book was released on 2013 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The manifestation of novel phenomena upon scaling to finite size has inspired a paradigm shift in materials science that takes advantage of the distinctive electrical and physical properties of nanomaterials. Remarkably, the simple honeycomb arrangement of carbon atoms in a single atomic layer has become renowned for exhibiting never-before-seen electronic and physical phenomena. This archetypal 2-dimensional nanomaterial is known as graphene, a single layer of graphite. Early reports in the 1950's eluded to graphene-like nanostructures that were evidenced from exfoliation of oxidized graphite followed by chemical reduction, absorbed carbon on transition metals, and thermal decomposition of SiC. Furthermore, the earliest tight binding approximation calculations in the 1950's held clues that a single-layer of graphite would behave drastically different than bulk graphite.^Not until 2004, when Giem and Novoselov first synthesized graphene by mechanical exfoliation from highly-oriented pyrolytic graphite did the field of graphene-based research bloom within the scientific community. Since 2004, the availability and relatively straight forward synthesis of single-layer graphene (SLG) enabled the observation of remarkable phenomena including: massless Dirac fermions, extremely high mobilities of its charge carriers, room temperature half-integer quantum Hall effect, the Rashba effect, and the potential for ballistic conduction over macroscopic distances. These enticing electronic properties produce the drive to study graphene for use in truly nanoscale electrical interconnects, integrated circuits, transparent conducting electrodes, ultra-high frequency transistors, and spintronic devices, just to name a few. Yet, for almost all real world applications graphene will need to be interfaced with other materials, metals, dielectrics, organics, or any combination thereof that in turn are constituted from various inorganic and organic components. Interfacing graphene, a nanomaterial with lateral dimensions in the hundreds of microns if not larger, with a corresponding atomic vertical thickness poses significant difficulties. Graphene's unique structure is dominated by surface area or potentially hybridized interfaces; consequently, the true realization of this remarkable nanomaterial in device constructs relies on engineering graphene interfaces at the surface in order to controllably mold the electronic structure. Near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy and the transmission mode analogue scanning transmission X-ray microscopy (STXM) are particularly useful tools to study the unoccupied states of graphene and graphene interfaces. In addition, polarized NEXAFS and STXM studies provide information on surface orientation, bond sterics, and the extent of substrate alignment before and after interfacial hybridization. The work presented in this dissertation is fundamentally informed by NEXAFS and STXM measurements on graphene/metal, graphene/dielectric, and graphene/organic interfaces. We start with a general review of the electronic structure of freestanding graphene and graphene interfaces in Chapter 1. In Chapter 2, we investigate freestanding single-layer graphene via STXM and NEXAFS demonstrating that electronic structure heterogeneities from synthesis and processing are ubiquitous in 2-dimensional graphene. We show the mapping of discrete charge transfer regions as a result of doped impurities that decorate the surfaces of graphene and that transfer processing imparts local electronic corrugations or ripples. In corroboration with density functional theory, definitive assignments to the spectral features, global steric orientations of the localized domains, and quantitative charge transfer schemes are evidenced. In the following chapters, we deliberately (Chapter 3) incorporate substitutional nitrogen into reduced graphene oxide to induce C‒N charge redistribution and improve global conductivity, (Chapter 4) fabricate graphene/metal interfaces and metal/graphene/metal sandwich structures evidencing classical anisotropic umpolung chemistry from carbon p z-orbrital charge pinning, and (Chapter 5) engineer graphene/dielectric interfaces showing electron depletion from carbon atoms at the HfOgraphene interface. The fabrication of graphene interfaces remains a critical gap for successful commercialization of graphene-based devices, yet we demonstrate that interfacial hybridization, anisotropic charge redistribution, local chemical bonding, and discrete electronic hybridization regimes play a critical role in the electronic structure at graphene interfaces.
Book Synopsis Theoretical Studies of the Growth, Stability and Applications of Atomically Precise Graphene Nanoribbons by : Zhongcan Xiao
Download or read book Theoretical Studies of the Growth, Stability and Applications of Atomically Precise Graphene Nanoribbons written by Zhongcan Xiao and published by . This book was released on 2019 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electronic Structure and Topological Quantum Phase Transitions in Strained Graphene Nanoribbons by : Fanyao Qu
Download or read book Electronic Structure and Topological Quantum Phase Transitions in Strained Graphene Nanoribbons written by Fanyao Qu and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this chapter, we discuss the new classes of matter, such as the quantum spin Hall (QSH) and quantum anomalous Hall (QAH) states, that have been theoretically predicted and experimentally observed in graphene and beyond graphene systems. We further demonstrate how to manipulate these states using mechanical strain, internal exchange field, and spin-orbit couplings (SOC). Spin-charge transport in strained graphene nanoribbons is also discussed assuming the system in the QAH phase, exploring the prospects of topological devices with dissipationless edge currents. A remarkable zero-field topological quantum phase transition between the time-reversal-symmetry-broken QSH and quantum anomalous Hall states is predicted, which was previously thought to take place only in the presence of external magnetic field. In our proposal, we show as the intrinsic SOC is tuned, how it is possible to two different helicity edge states located in the opposite edges of the graphene nanoribbons exchange their locations. Our results indicate that the strain-induced pseudomagnetic field could be coupled to the spin degrees of freedom through the SOC responsible for the stability of a QSH state. The controllability of this zero-field phase transition with strength and direction of the strain is also explored as additional phase-tuning parameter. Our results present prospect of strain, electric and magnetic manipulation of the QSH, and QAH effect in these novel two-dimensional (2D) materials.
