Download or read book Crystal Growth of Graphene Films and Graphene Nanoribbons Via Chemical Vapor Deposition written by Robert Michael Jacobberger and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene is a two-dimensional carbon allotrope that has exceptional properties, including high charge carrier mobility, thermal conductivity, mechanical strength, and flexibility. Graphene is a semimetal, prohibiting its use in semiconductor applications in which a bandgap is required. However, graphene can be transformed from a semimetal into a semiconductor if it is confined into one-dimensional nanoribbons narrower than 10 nm with well-defined armchair edges. In this work, we study the crystal growth of graphene via chemical vapor deposition (CVD), which is the most promising method to produce graphene films on the industrial scale. We explore the growth of isolated graphene crystals, continuous graphene films, and narrow graphene nanoribbons with armchair edges. We gain key insight into the critical growth parameters and mechanisms that influence the crystal morphology, orientation, defect density, and evolution, providing an empirical understanding of the diverse growth behaviors observed in literature. Using this knowledge, we synthesize graphene with remarkably low pinhole density and achieve high-quality graphene at 750 [degrees]C on Cu(111), which is over 250 [degrees]C lower than the temperature typically used to grow graphene on copper from methane. We also describe our breakthrough in graphene nanoribbon synthesis. Highly anisotropic nanoribbons are formed on Ge(001) if an exceptionally slow growth rate is used. The nanoribbons are self-defining with predominantly smooth armchair edges, are self-aligning, and have tunable width to 10 nm. High-performance field-effect transistors incorporating these nanoribbons as channels display high conductance modulation 10,000 and high conductance> 5 [mu]S. This directional and anisotropic growth enables the fabrication of semiconducting nanoribbons directly on conventional semiconductor wafers and, thus, promises to allow the integration of nanoribbons into future hybrid integrated circuits. We additionally report our discovery that chemical patterns consisting of alternating stripes of graphene and germanium can direct the self-assembly of block copolymers into rationally-designed patterns with nanoscale features. Density multiplication of 10 is achieved and faster assembly kinetics are observed on graphene/germanium templates than on conventional chemical patterns based on polymer mats and brushes. This work opens the door for extensive assembly studies on chemical patterns based on two-dimensional materials.
Download or read book 2D Materials written by Phaedon Avouris and published by Cambridge University Press. This book was released on 2017-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about the most recent advances in 2D materials with this comprehensive and accessible text. Providing all the necessary materials science and physics background, leading experts discuss the fundamental properties of a wide range of 2D materials, and their potential applications in electronic, optoelectronic and photonic devices. Several important classes of materials are covered, from more established ones such as graphene, hexagonal boron nitride, and transition metal dichalcogenides, to new and emerging materials such as black phosphorus, silicene, and germanene. Readers will gain an in-depth understanding of the electronic structure and optical, thermal, mechanical, vibrational, spin and plasmonic properties of each material, as well as the different techniques that can be used for their synthesis. Presenting a unified perspective on 2D materials, this is an excellent resource for graduate students, researchers and practitioners working in nanotechnology, nanoelectronics, nanophotonics, condensed matter physics, and chemistry.
Download or read book Seed mediated Growth of Graphene Nanoribbons on Germanium Via Chemical Vapor Deposition written by Austin James Way and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene nanoribbons possess exceptional electrical and thermal properties, among other unique qualities, which makes them a material of interest for next-generation electronics such as high-frequency communication devices, logic circuits, optoelectronics, photonics, and sensors. Unlike graphene, which is a semimetal, graphene nanoribbons can be semiconducting when they possess a width less than 10 nm. However, the difficulty of synthesizing ribbons with the qualities required for device applications has remained a challenge. Ribbons must have sub-10 nm widths, lengths greater than 100 nm, controlled orientation and placement, and a smooth, armchair edge structure for reliable integration in semiconductor electronics. Additionally, the synthesis must be scalable and on a technologically relevant substrate. While many fabrication techniques exist, none have been able to achieve all of the necessary characteristics. In this work, we develop novel nanoribbon fabrication routes to address these challenges and advance our knowledge of graphene synthesis on Ge(001) via chemical vapor deposition. We explore the concept of seeding nanoribbon growth through integration of lithographically patterned graphene seeds, delve into the interactions of graphene seeds with the Ge surface and adjacent seeds, and advance the approach through the use of monodisperse small molecule seeds. We find that the use of graphene seeds provides control over where crystal growth occurs, allows crystal orientations that are unobserved naturally on Ge(001), and decouples the effects of nucleation and growth. We discover that the angle between armchair orientation of lithographically patterned graphene seeds with the Ge[110] family of directions dictates the resulting nanoribbon's orientation and anisotropy. By aligning these directions, the growth anisotropy is maximized and high-aspect ratio nanoribbons result; however, when the directions are misaligned, a low aspect ratio crystal occurs. Utilizing this knowledge, we construct a plot analogous to a Kinetic Wulff plot that predicts the shape and anisotropy of the graphene crystal growth on Ge(001). By manipulating the seeds favorably, we fabricate unidirectional arrays of graphene nanoribbons with precise placement and greatly reduced polydispersity in the length and width, as compared to non-seeded ribbon growth. This work provides a framework toward the fabrication of wafer-scale arrays of semiconducting, armchair graphene nanoribbons with controlled placement and orientation with potential application in a variety of semiconductor technologies. Through improvement of our seed-initiated synthesis process, we garner greater understanding of the graphene nanoribbon growth regime and the influence of pitch (seed to seed distance) and seed size on nanoribbon characteristics. Experimental results show that growth kinetics are invariant to pitches as low as 50 nm and in conjunction with computational modeling, indicate that the kinetics are either strongly attachment limited or the diffusion length of the growth species is much less than 50 nm. Additionally, periodic arrays of nanoribbons are successfully fabricated from graphene seeds with sub-5 nm diameters, resulting in sub-10 nm nanoribbon widths. This advancement enables nanoribbons with sub-10 nm widths to be fabricated with pitches lower than 50 nm, promising improved integration in hybrid integrated circuits. We also report our discovery of seed rotation on Ge(001) as a function of seed diameter and orientation. While previous results demonstrated that misaligned seeds result in low aspect ratio crystals, we find that high aspect ratio ribbons can result if the seed diameter is small enough. A critical seed diameter of 18 nm is determined for seed rotation to occur. We determine that seeds preferentially rotate to the nearest Ge 110 direction. Utilizing this knowledge, nanoribbon meshes with sub-10 nm widths are fabricated. These results suggest the potential to created meshes, interconnects, and other unique architectures for various device applications. Utilizing the knowledge of our previous seeding work, we report the successful growth of graphene nanoribbons via molecular seeds. Through manipulation of the growth conditions, nanoribbons narrower than 5 nm, and as low as 2.5 nm, are synthesized on Ge(001). The nanoribbons possess long segments of armchair edges and demonstrate a nearly three times improvement on width polydispersity, as compared to non-seeded nanoribbon synthesis. Leveraging this uniformity control, nanoribbons with 3.5 and 6.1 nm widths are produced and integrated into field effect transistors, which demonstrate an on/off ratio that differs by two order of magnitude due to the difference in width. This groundbreaking work opens the door for extensive experimental studies on the impact of molecular seed type, the potential of molecular seeds as dopants, the origin and nature of nanoribbon growth on Ge(001), as well as potential application on other two-dimensional materials.
Download or read book The Synthesis and Application of Chemical Vapor Deposited Graphene written by Jaime Antonio Torres and published by . This book was released on 2014 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene is one of the most amazing materials every discovered. It is the first stable two-dimensional crystal ever studied and has broadly impacted a myriad of fields ranging from physical science to engineering. Science has made such great advancements due to graphene that its discovery earned Nobel recognition in 2010. Initially isolated from bulk graphite using cellophane tape, its use in macroscale applications requires methods to produce it in high quality and on a very large scale. This synthetic problem is the basis for this thesis whereby the scalable synthesis and application of graphene is demonstrated utilizing chemical vapor deposition (CVD). Mono-carbon containing methane gas is the most utilized carbon precursor for the CVD growth of graphene. To study the effects of other hydrocarbon precursor gases, graphene was grown by chemical vapor deposition from methane, ethane, and propane on copper foils. The larger molecules were found to more readily produce bilayer and multilayer graphene, due to a higher carbon concentration and different decomposition processes. Single- and bilayer graphene was grown with good selectivity in a simple, single-precursor process by varying the pressure of ethane from 250 to 1000 mTorr as characterized by Raman spectroscopy. The bilayer graphene is AB-stacked as shown by selected area electron diffraction analysis. Vertically oriented structures of conductors and semiconductors, especially single crystals, are of great technological importance due to their directional and rapid charge carrier transport yet there does not exist a facile way to produce them. Here, we report a facile, solution-based "bottom-up" route for producing highly oriented, single crystalline, vertical arrays of conjugated molecules that exhibit uniform morphological and crystallographic orientations by employing a layer of graphene as a guiding substrate. Using an oligoaniline as model, we demonstrate that this method is highly versatile, allows for precision growth and deposition of crystals by first patterning the growth graphene substrates, and allows for the anisotropic transport of charged carriers to efficiently reach a conductivity of 12.3 S/cm along the vertical axis, the highest reported to date for an aniline oligomer. Large-area devices where current from individual crystals can be collectively harnessed are demonstrated, illustrating its promise for both micro- and macro-scopic device applications. The transfer of large sheets of graphene is desired for a variety of applications including electronics and membrane technology. Currently, CVD grown graphene is isolated from a growth catalyst by use of polymer-assisted transfer. The underlying growth catalyst is etched away while the polymer acts as a support for transfer to arbitrary substrates before it is removed chemically and by high temperature annealing. While transferring graphene onto rigid substrates that can survive post-processing high temperature anneals is possible, the same is not true for plastic and flexible substrates. The use of the polymer may lead to unwanted contamination and damaged graphene films. We demonstrate a way to transfer very large sheets of graphene tailored for thickness onto flexible and porous membranes supports for use in size selective filtration. We utilize optimized concentrations of ammonium persulfate to etch graphene grown on Cu-Ni alloys to produce polymer-free graphene film that can be transferred onto arbitrary substrates.
Download or read book Graphene written by Wonbong Choi and published by CRC Press. This book was released on 2016-04-19 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the late 20th century, graphene-a one-atom-thick planar sheet of sp2-bonded carbon atoms densely packed in a honeycomb crystal lattice-has garnered appreciable attention as a potential next-generation electronic material due to its exceptional properties. These properties include high current density, ballistic transport, chemical inertness,
Download or read book Carbon nanotubes and graphene for photonic applications written by E. Einarsson and published by Elsevier Inc. Chapters. This book was released on 2013-08-31 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter provides an overview of methods used to synthesize single-walled carbon nanotubes (SWNTs) and graphene. Synthesis methods of commercially available SWNTs are reviewed first, followed by common in-house methods. Historically important approaches are discussed but the focus is on tailored synthesis by chemical vapor deposition (CVD). Primary routes for graphene synthesis are described next, in addition to background regarding the discovery of this two-dimensional material. Exfoliation of graphite into single-layer graphene is described, followed by synthesis routes involving reduction of graphene oxide and epitaxial growth from carbides. The chapter ends with an overview of CVD synthesis of graphene on metal substrates.
Download or read book Graphene written by Viera Skakalova and published by Elsevier. This book was released on 2014-02-16 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene: Properties, Preparation, Characterisation and Devices reviews the preparation and properties of this exciting material. Graphene is a single-atom-thick sheet of carbon with properties, such as the ability to conduct light and electrons, which could make it potentially suitable for a variety of devices and applications, including electronics, sensors, and photonics. Chapters in part one explore the preparation of , including epitaxial growth of graphene on silicon carbide, chemical vapor deposition (CVD) growth of graphene films, chemically derived graphene, and graphene produced by electrochemical exfoliation. Part two focuses on the characterization of graphene using techniques including transmission electron microscopy (TEM), scanning tunneling microscopy (STM), and Raman spectroscopy. These chapters also discuss photoemission of low dimensional carbon systems. Finally, chapters in part three discuss electronic transport properties of graphene and graphene devices. This part highlights electronic transport in bilayer graphene, single charge transport, and the effect of adsorbents on electronic transport in graphene. It also explores graphene spintronics and nano-electro-mechanics (NEMS). Graphene is a comprehensive resource for academics, materials scientists, and electrical engineers working in the microelectronics and optoelectronics industries. Explores the graphene preparation techniques, including epitaxial growth on silicon carbide, chemical vapor deposition (CVD), chemical derivation, and electrochemical exfoliation Focuses on the characterization of graphene using transmission electron microscopy (TEM), scanning tunneling microscopy (STM), and Raman spectroscopy A comprehensive resource for academics, materials scientists, and electrical engineers
Download or read book Graphene Science Handbook written by Mahmood Aliofkhazraei and published by CRC Press. This book was released on 2016-04-27 with total page 587 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores Chemical-Based, Non-Chemical Based, and Advanced Fabrication MethodsThe 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, photovolt
Download or read book Epitaxial Graphene on Silicon Carbide written by Gemma Rius and published by CRC Press. This book was released on 2018-01-19 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book dedicated exclusively to epitaxial graphene on silicon carbide (EG-SiC). It comprehensively addresses all fundamental aspects relevant for the study and technology development of EG materials and their applications, using quantum Hall effect studies and probe techniques such as scanning tunneling microscopy and atomic resolution imaging based on transmission electron microscopy. It presents the state of the art of the synthesis of EG-SiC and profusely explains it as a function of SiC substrate characteristics such as polytype, polarity, and wafer cut as well as the in situ and ex situ conditioning techniques, including H2 pre-deposition annealing and chemical mechanical polishing. It also describes growth studies, including the most popular characterization techniques, such as ultrahigh-vacuum, partial-pressure, or graphite-cap sublimation techniques, for high-quality controlled deposition. The book includes relevant examples on synthesis and characterization techniques as well as device fabrication processing and performance and complements them with theoretical modeling and simulation studies, which are helpful in the fundamental comprehension of EG-SiC substrates and their potential use in electronic applications. It addresses the fundamental aspects of EG-SiC using quantum Hall effect studies as well as probe techniques, such as scanning tunneling microscopy or atomic resolution imaging based on transmission electron microscopy. It comprises chapters that present reviews and vision on the current state of the art of experts in physics, electronic engineering, materials science, and nanotechnology from Europe and Asia.
Download or read book Chemical Vapor Deposition CVD Growth and Optimal Transfer Processes for Graphene written by Seong Soon Jo and published by . This book was released on 2018 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene has been regarded as a good candidate to make a breakthrough in various applications including electronics, sensors and spintronics due to its exceptional physical properties. To realize those practical applications, a high quality homogeneous wafer-scale graphene is required. Among various synthesis methods, chemical vapor deposition (CVD) has been a focus of attention as the most promising and cost-efficient deposition techniques, with advantages of its excellent repeatability and controllability, to produce large area graphene crystals on transition metal catalyst substrates. In particular, Cu with low carbon solid solubility is suitable to obtain uniform single layer deposition of graphene over large areas. Here, we report reliable method to grow high-quality continuous graphene film by CVD. Their surface properties and electrical transport characteristics are explored by several characterization techniques. In CVD process, furthermore, a subsequent transfer process to a substrate of interest is required for a wide variety of applications, especially in electronics and photonics, because the metal substrates necessary to catalyze the CVD graphene growth cannot be used. It is important not only to improve quality of as-grown graphene by optimizing growth system but also to develop transfer methods to prevent degradation in quality while transferring as-grown graphene to target substrates. In the case of wet transfer, surface tension of the liquid such as an etching agent or water contributes to make inevitable ripples, wrinkles and cracks. In this regard, we demonstrate new transfer methods by selecting a new polymeric support materials in order to reduce the number of winkles, defects and residues.
Download or read book Graphene Materials written by George Z. Kyzas and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Graphene and Other 2D Layered Nanomaterial Based Films written by Federico Cesano and published by MDPI. This book was released on 2019-12-12 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to highlighting some relevant advances in the field of thin films and coatings based on two-dimensional crystals and layered nanomaterials. Due to their layered structure, graphene and a variety of new 2D inorganic nanosystems, called “graphene analogues”, have all attracted tremendous interest due to their unprecedented properties/superior performance, and may find applications in many fields from electronics to biotechnology. These two-dimensional systems are ultrathin and, hence, tend to be flexible, also presenting distinctive and nearly intrinsic characteristics, including electronic, magnetic, optical, thermal conductivity, and superconducting properties. Furthermore, the combination of different structures and synergetic effects may open new and unprecedented perspectives, making these ideal advanced materials for multifunctional assembled systems. As far as the field of coatings is concerned, new layered nanostructures may offer unique and multifunctional properties, including gas barrier, lubricant, conductive, magnetic, photoactive, self-cleaning, and/or antimicrobial surfaces. This book contains new findings on the synthesis and perspectives of multifunctional films that are at the forefront of the science and coating technologies.
Download or read book Large Area Synthesis and Growth Mechanism of Graphene by Chemical Vapor Deposition written by GuiPing Dai and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been continuous progress in the development of different synthesis methods to readily produce graphene at a lower cost. Compared with the other methods, chemical vapor deposition (CVD) is an effective and powerful method of producing graphene and has attracted increased attention during the last decade. In this way, we can obtain good uniformity with a multitude of domains, excellent quality, and large scale of the produced graphene. Meanwhile, it is also helping for large-area synthesis of single-crystal graphene. In the CVD method, precursors are typically absorbed on the surface followed by pyrolytic decomposition, which leads to the generation of absorption sites on the surface and promotes the growth of continuous thin films.
Download or read book Graphene Growth on Low Carbon Solubility Metals written by Joseph Monroe Wofford and published by . This book was released on 2012 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in synthesis are imperative if graphene is to fulfill its scientific and technological potential. Single crystal graphene of is currently available only in the small flakes generated by mechanical exfoliation. Layers of larger size may be grown either by the thermal decomposition of SiC or by chemical vapor deposition on metals. However, as they are currently implemented, these methods yield graphene films of inferior quality. Thus the requirement for wafer-scale, high-quality graphene films remains unmet. This dissertation addresses this issue by examining graphene growth on metal surfaces. Through a survey of the fundamental underlying processes, it provides guidance for improving the quality of the resulting graphene films. Graphene was grown on Cu(100), Cu(111), and Au(111) by physical vapor deposition of elemental C. The nucleation and growth behaviors of graphene were evaluated by low-energy electron microscopy. Graphene tends to nucleate heterogeneously at surface imperfections although it also does so homogeneously on Cu(111) and Au(111). Graphene growing on Cu(100) is governed by the attachment kinetics of C at the propagating crystal front. The resulting angularly dependent growth rate sculpts individual crystals into elongated lobes. In contrast, graphene growth on both Cu(111) and Au(111) is surface diffusion limited. This yields ramified, dendritic graphene islands. Graphene films grown on Cu(100) contain significant rotational disorder. This disorder is partially attributable to the symmetry mismatch between film and substrate. The common symmetry between graphene and Cu(111) contributes to a significant reduction in disorder in films grown on this surface. Most graphene domains occupy a 6̃o arc of orientations. On Au(111) the vast majority of graphene domains are locked into alignment with the substrate surface. The extraordinary extent of their orientational homogeneity is such that the resulting graphene film is a quasi-single crystal. The findings presented illustrate how metal species and crystal symmetry influence the structural properties of monolayer graphene. The selection of an optimal substrate for graphene growth can significantly reduce crystalline disorder in the resulting film.
Download or read book Growing Graphene on Semiconductors written by Nunzio Motta and published by CRC Press. This book was released on 2017-09-08 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene, the wonder material of the 21st century, is expected to play an important role in future nanoelectronic applications, but the only way to achieve this goal is to grow graphene directly on a semiconductor, integrating it in the chain for the production of electronic circuits and devices. This book summarizes the latest achievements in this field, with particular attention to the graphitization of SiC. Through high-temperature annealing in a controlled environment, it is possible to decompose the topmost SiC layers, obtaining quasi-ideal graphene by Si sublimation with record electronic mobilities, while selective growth on patterned structures makes possible the opening of a gap by quantum confinement. The book starts with a review chapter on the significance and challenges of graphene growth on semiconductors, followed by three chapters dedicated to an up-to-date analysis of the synthesis of graphene in ultrahigh vacuum, and concludes with two chapters discussing possible ways of tailoring the electronic band structure of epitaxial graphene by atomic intercalation and of creating a gap by the growth of templated graphene nanostructures.
Download or read book Oriented Bottom up Growth of Armchair Graphene Nanoribbons on Germanium written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene nanoribbon arrays, methods of growing graphene nanoribbon arrays and electronic and photonic devices incorporating the graphene nanoribbon arrays are provided. The graphene nanoribbons in the arrays are formed using a scalable, bottom-up, chemical vapor deposition (CVD) technique in which the (001) facet of the germanium is used to orient the graphene nanoribbon crystals along the [110] directions of the germanium.
Download or read book Germanium Based Technologies written by Cor Claeys and published by Elsevier. This book was released on 2011-07-28 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: Germanium is a semiconductor material that formed the basis for the development of transistor technology. Although the breakthrough of planar technology and integrated circuits put silicon in the foreground, in recent years there has been a renewed interest in germanium, which has been triggered by its strong potential for deep submicron (sub 45 nm) technologies. Germanium-Based technologies: From Materials to Devices is the first book to provide a broad, in-depth coverage of the field, including recent advances in Ge-technology and the fundamentals in material science, device physics and semiconductor processing. The contributing authors are international experts with a world-wide recognition and involved in the leading research in the field. The book also covers applications and the use of Ge for optoelectronics, detectors and solar cells. An ideal reference work for students and scientists working in the field of physics of semiconductor devices and materials, as well as for engineers in research centres and industry. Both the newcomer and the expert should benefit from this unique book. State-of-the-art information available for the first time as an all-in-source Extensive reference list making it an indispensable reference book Broad coverage from fundamental aspects up to industrial applications
