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Variable Temperature Scanning Tunneling Microscopy Studies Of Growth And Characterization Of Hexagonal Boron Nitride And Graphene Layers
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Book Synopsis Variable-Temperature Scanning Tunneling Microscopy Studies of Growth and Characterization of Hexagonal Boron Nitride and Graphene Layers by : Pedro Arias
Download or read book Variable-Temperature Scanning Tunneling Microscopy Studies of Growth and Characterization of Hexagonal Boron Nitride and Graphene Layers written by Pedro Arias and published by . This book was released on 2019 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-dimensional (2D) materials, such as graphene and hexagonal boron nitride (hBN) have attracted attention from both academia and industry owing to their unique atomically thin structure and associated properties. The goal of this dissertation is to provide fundamental insights of the growth kinetics, surface structure, and thermal stability of hBN and graphene layers grown via chemical vapor deposition (CVD) on metal substrates. Scanning tunneling microscopy (STM) was used to investigate the surface structure of hexagonal boron nitride (hBN) domains on Pd(111) grown via dissociative chemisorption of borazine on Pd(111)/Al2O3(0001) thin films. STM images acquired from the hBN/Pd(111) sample reveal moir patterns with different periodicities corresponding to rotational domains of hBN. Surface corrugations in each of the moir patterns were measured from the STM images as a function of the STM tunneling parameters. The corrugation amplitude z was found to depend on the tunneling bias and increases with increasing . The observed tunneling-parameter dependence in z were attributed to the electronic structure of the hBN/Pd(111) system. The domains with the largest , exhibit a bifurcation behavior in which some domains are nearly flat, and others develop "blisters", i.e., significant hills-and-valley geometric undulations. Hence, unlike any other monolayer hBN-on-metal system, hBN/Pd can have either mainly geometric or mainly electronic corrugation, depending on the domain orientation. The growth kinetics of hBN monolayers grown via CVD using borazine (B3N3H6) on Pd(111) were investigated using in situ variable-temperature STM. STM images were acquired during CVD of borazine on Pd(111) as a function of the substrate temperature T, the borazine partial pressure P, and time t. The STM images reveal a T and P dependent change in the growth mode: at higher P and lower T, (lower P and higher T), hBN nucleation occurs primarily on Pd step edges (Pd terraces). Furthermore, the mechanisms promoting growth across the step edges (as a carpet across steps) are identified. These results provide new insights into the nucleation and growth of hBN monolayers and potentially other 2D materials and related heterostructures on metal substrates. The thermal stability of hBN covered Pd(111) thin films was investigated using in situ variable-temperature STM. STM images were acquired from bare Pd(111) and hBN covered Pd(111) at temperatures between 600 K and 1000 K. It was found that the hBN overlayer enhances the stability of the underlying Pd surface by suppressing the surface mobility of adatoms. These results provide new, direct insights into the behavior of substrate supported 2D materials at elevated temperatures. Finally, in situ VT-STM was used to investigate the growth of graphene using benzene (C6H6) on Pd(111). STM images were acquired during and after benzene deposition at temperatures between 300 K and 1100 K. Compared to growth of graphene on Pd(111) using other hydrocarbon precursors (e.g. ethylene), benzene enables the growth of graphene at lower T, and at significantly lower doses, likely due to an increased probability of forming C6 and/or C6Hx(x
Book Synopsis Controlled Synthesis and Scanning Tunneling Microscopy Study of Graphene and Graphene-Based Heterostructures by : Mengxi Liu
Download or read book Controlled Synthesis and Scanning Tunneling Microscopy Study of Graphene and Graphene-Based Heterostructures written by Mengxi Liu and published by Springer. This book was released on 2017-10-10 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the energy band engineering of graphene. It presents pioneering findings on the controlled growth of graphene and graphene-based heterostructures, as well as scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS) studies on their electronic structures. The thesis primarily investigates two classes of graphene-based systems: (i) twisted bilayer graphene, which was synthesized on Rh substrates and manifests van Hove singularities near Fermi Level, and (ii) in-plane h-BN-G heterostructures, which were controllably synthesized in an ultrahigh vacuum chamber and demonstrate intriguing electronic properties on the interface. In short, the thesis offers revealing insights into the energy band engineering of graphene-based nanomaterials, which will greatly facilitate future graphene applications.
Book Synopsis Chemical Vapour Deposition Growth of Graphene and Hexagonal Boron Nitride, and a Study of the Electronic and Corrosion Inhibiting Properties of Hexagonal Boron Nitride by : Farzaneh Mahvash Mohammadi
Download or read book Chemical Vapour Deposition Growth of Graphene and Hexagonal Boron Nitride, and a Study of the Electronic and Corrosion Inhibiting Properties of Hexagonal Boron Nitride written by Farzaneh Mahvash Mohammadi and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Graphene is an allotrope of carbon in the form of a two-dimensional (2D) material with zero bandgap. Hexagonal boron nitride (hBN), also known as white graphite, is a wide bandgap 2D material that has found use as an insulating dielectric layer in ultra-high mobility graphene devices, 2D heterostructures and tunneling devices. In this thesis, we report the chemical vapor deposition (CVD) growth and characterization of graphene and monolayer hBN. The growth of graphene and hBN was performed separately in a tube furnace on Cu foils using methane (CH4) and an ammonia borane (NH3-BH3) precursor, respectively. Raman spectroscopy confirmed that the CVD grown graphene is a monolayer of high quality. We have fabricated graphene field effect transistors and characterized their electrical properties to demonstrate material quality. Additionally, the CVD grown graphene was incorporated in a diverse range of applications, including large area graphene ion sensitive field effect transistors, suspended graphene varactors and an investigation of the role of hydrogenation on the electronic and thermal properties of graphene. We employed a variety of techniques to characterize CVD grown hBN. The morphology of the as-grown film along with the optimization of growth conditions to yield high coverage of monolayer hBN was studied by scanning electron microscopy. X-ray photoelectron spectroscopy confirmed the presence of boron and nitrogen in the CVD grown film as well as the expected stoichiometry. The electron diffraction pattern of suspended hBN films displayed a hexagonal crystal structure. A prominent Stokes Raman shift at 1369 cm-1 was observed in hBN transferred to Si/SiO2 substrates, revealing that our CVD grown hBN is of monolayer form. The optical properties of our hBN layers were probed by cathodoluminescence and UV-visible absorption spectroscopy. We report the first observation of in-plane charge transport in large area CVD grown monolayer hBN using a variety of electrode geometries. Ni electrodes were used to provide electrical contacts. We have observed a quadratic scaling of current with voltage at high bias corresponding to a space charge limited conduction mechanism, with a room temperature mobility reaching up to 0.01 cm2/Vs at electric fields up to 100 kV/cm in the absence of dielectric breakdown. The observation of in-plane charge transport highlights the semiconducting nature of monolayer hBN, and identifies hBN as a wide-gap 2D crystal capable of supporting charge transport at high field. Furthermore, we have examined the suitability of CVD grown monolayer hBN for inhibiting corrosion. Quantitative measurements of monolayer hBN as a Cu corrosion inhibitor were studied by use of cyclic voltammetry, Tafel analysis and electrochemical impedance spectroscopy. We have found that CVD grown monolayer hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating.The final contribution of this thesis is the growth of hBN directly on Si/SiO2 substrate via CVD. The main focus of this work is to produce metal-free, large-area, continuous and uniform hBN dielectric films on Si-based substrates ready to incorporate into devices without any transfer processing. We have also examined the effect of carrier gas flow rate on the thickness and roughness of the grown film in atmospheric pressure CVD. We have succeeded to grow large area hBN films with the thickness of ~ 2 nm and rms roughness of 0.6 nm (over 1 μm2) directly on Si/SiO2 substrates via atmospheric pressure CVD." --
Book Synopsis Scanning Tunneling Microscopy in Surface Science, Nanoscience, and Catalysis by : Michael Bowker
Download or read book Scanning Tunneling Microscopy in Surface Science, Nanoscience, and Catalysis written by Michael Bowker and published by John Wiley & Sons. This book was released on 2009-11-11 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, top international authors in the field of STM and surface science present first-class contributions on this hot topic, bringing the reader up to date with the latest developments in this rapidly advancing field. The focus is on the nanoscale, particularly in relation to catalysis, involving developments in our understanding of the nature of the surfaces of oxides and nanoparticulate materials, as well as adsorption, and includes in-situ studies of catalysis on such model materials. Of high interest to practitioners of surface science, nanoscience, STM and catalysis.
Book Synopsis Fabrication and Characterization of Single-layer Graphene Transferred on Hexagonal Boron Nitride by : Mingwei Zhang
Download or read book Fabrication and Characterization of Single-layer Graphene Transferred on Hexagonal Boron Nitride written by Mingwei Zhang and published by . This book was released on 2013 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Graphene written by Viera Skakalova and published by Woodhead Publishing. This book was released on 2021-06-23 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene: Properties, Preparation, Characterization and Devices, Second Edition, provides a comprehensive look at the methods used to prepare and analyze graphene. Since the first edition’s publication, there have been many advances in the understanding of graphene, in particular, its key properties and most relevant applications. Updates to this new edition include chapters on liquid exfoliation production of graphene and scanning transmission electron microscopy of graphene. New sections cover graphene's thermal, optical, mechanical, chemical and biocompatibility, with special attention paid to transport properties, a main barrier to the realization of commercial applications. Reviews the preparation and characterization of graphene, covering the latest advances in liquid exfoliation production and the scanning transmission electron microscopy of graphene Includes a new section dedicated to the properties of graphene (thermal, transport, optical, mechanical, chemical) to reflect the latest understanding of this important material Discusses the most relevant applications of graphene, such as biomedical, sensing, energy and electronic applications
Book Synopsis Growth of Atomic Hexagonal Boron Nitride Layers and Graphene/hexagonal Boron Nitride Heterostructures by Molecular Beam Epitaxy by : Zhongguang Xu
Download or read book Growth of Atomic Hexagonal Boron Nitride Layers and Graphene/hexagonal Boron Nitride Heterostructures by Molecular Beam Epitaxy written by Zhongguang Xu and published by . This book was released on 2016 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following with the lateral growth of graphene on in situ epitaxial h-BN flakes by plasma-assisted MBE is discussed in Chapter 4. Single-crystal h-BN domains were grown on Co film substrates at a substrate temperature of 850~900 oC using plasma-assisted MBE. Three-point star shape h-BN domains were observed by SEM, and confirmed by Raman and XPS. The h-BN on Co template was used for in situ growth of multilayer graphene, leading to an h-BN/graphene heterostructure. Carbon atoms preferentially nucleate on Co substrate and edges of h-BN and then grow laterally to form continuous graphene. Further introduction of carbon atoms results in layer-by-layer growth of graphene on graphene and lateral growth of graphene on h-BN until it may cover entire h-BN flakes.
Book Synopsis Experimental Investigation of Thermal Transport in Graphene and Hexagonal Boron Nitride by : Insun Jo
Download or read book Experimental Investigation of Thermal Transport in Graphene and Hexagonal Boron Nitride written by Insun Jo and published by . This book was released on 2012 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-dimensional graphene, a single layer of graphite, has emerged as an excellent candidate for future electronic material due to its unique electronic structure and remarkably high carrier mobility. Even higher carrier mobility has been demonstrated in graphene devices using hexagonal boron nitride as an underlying dielectric support instead of silicon oxide. Interestingly, both graphene and boron nitride exhibit superior thermal properties, therefore may potentially offer a solution to the increasingly severe heat dissipation problem in nanoelectronics caused by increased power density. In this thesis, we focus on the investigation of the thermal properties of graphene and hexagonal boron nitride. First, scanning thermal microscopy based on a sub-micrometer thermocouple at the apex of a microfabricated tip was employed to image the temperature profiles in electrically biased graphene devices with ~ 100 nm scale spatial resolution. Non-uniform temperature distribution in the devices was observed, and the "hot spot" locations were correlated with the charge concentrations in the channel, which could be controlled by both gate and drain-source biases. Hybrid contact and lift mode scanning has enabled us to obtain the quantitative temperature profiles, which were compared with the profiles obtained from Raman-based thermometry. The temperature rise in the channel provided an important insight into the heat dissipation mechanism in Joule-heated graphene devices. Next, thermal conductivity of suspended single and few-layer graphene was measured using a micro-bridge device with built-in resistance thermometers. Polymer-assisted transfer technique was developed to suspend graphene layers on the pre-fabricated device. The room temperature thermal conductivity values of 1-7 layer graphene were measured to be lower than that of bulk graphite, and the value appeared to increase with increasing sample thickness. These observations can be explained by the impact of the phonon scattering by polymer residue remaining on the sample surfaces. Lastly, thermal conductivity of few-layer hexagonal boron nitride sample was measured by using the same device and technique used for suspended graphene. Measurements on samples with different suspended lengths but similar thickness allowed us to extract the intrinsic thermal conductivity of the samples as well as the contribution of contact thermal resistance to the overall thermal measurement. The room temperature thermal conductivity of 11 layer sample approaches the basal-plane value reported in the bulk sample. Lower thermal conductivity was measured in a 5 layer sample than an 11 layer sample, which again supports the polymer effect on the thermal transport in few-layer hexagonal boron nitride.
Book Synopsis Scanning Tunneling Microscopy and Spectroscopy Studies of Graphene by : Adina Luican-Mayer
Download or read book Scanning Tunneling Microscopy and Spectroscopy Studies of Graphene written by Adina Luican-Mayer and published by . This book was released on 2012 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the two-dimensional (2D) lattice of graphene, consisting of carbon atoms arranged in a honeycomb lattice, the charge carriers are described by a Dirac-Weyl Hamiltonian. Seeking to understand their unique nature, this thesis presents results of scanning tunneling microscopy (STM) and spectroscopy (STS) experiments at low temperatures and in magnetic fi eld. These techniques give access, down to atomic scales, to structural information as well as to the electronic properties of graphene. The main findings include the observation of quantized Landau levels (LL) in the presence of magnetic field, their dependence on carrier density and e ffects of charged impurities and other disorder on the LL spectrum. Twisting graphene layers away from the equilibrium Bernal stacking leads to the formation of Moir e patterns that signi ficantly alter the electronic properties of graphene stacks. The second part of the thesis discusses the eff ects of such rotations on the electronic properties as a function of twist angle.
Book Synopsis Formation of Graphene and Hexagonal Boron Nitride on Rh(111) Studied by In-situ Scanning Tunnelling Microscopy by : Guocai Dong
Download or read book Formation of Graphene and Hexagonal Boron Nitride on Rh(111) Studied by In-situ Scanning Tunnelling Microscopy written by Guocai Dong and published by . This book was released on 2012 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scanning Tunneling Microscopy Studies of Growth Medium and Temperature Dependent Structural Phases of Alkanethiol Self-assembled Monolayers, Reactive Self-assembled Monolayers, and Flat Gold Nanoparticle/indium Tin Oxide Substrates and a Scanning Surface Photovoltage Microscopy Study for Local Mechanical Stress Characterization in Complementary Metal Oxide Semiconductor Devices by : Dahanayaka Liyanage Daminda Hemal Dahanayaka
Download or read book Scanning Tunneling Microscopy Studies of Growth Medium and Temperature Dependent Structural Phases of Alkanethiol Self-assembled Monolayers, Reactive Self-assembled Monolayers, and Flat Gold Nanoparticle/indium Tin Oxide Substrates and a Scanning Surface Photovoltage Microscopy Study for Local Mechanical Stress Characterization in Complementary Metal Oxide Semiconductor Devices written by Dahanayaka Liyanage Daminda Hemal Dahanayaka and published by . This book was released on 2010 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis In Situ High-temperature Scanning Tunneling Microscopy Studies of Early Stage Growth Kinetics During TiN Epitaxy by : Suneel Kumar Kodambaka
Download or read book In Situ High-temperature Scanning Tunneling Microscopy Studies of Early Stage Growth Kinetics During TiN Epitaxy written by Suneel Kumar Kodambaka and published by . This book was released on 2002 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Variable-temperature scanning tunneling microscopy studies of atomic and molecular level surface phenomena on semiconductor and metal surfaces by : William Patrick Fitts
Download or read book Variable-temperature scanning tunneling microscopy studies of atomic and molecular level surface phenomena on semiconductor and metal surfaces written by William Patrick Fitts and published by . This book was released on 2001 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Graphene-substrate Interactions Using Scanning Tunneling Microscopy by :
Download or read book Characterization of Graphene-substrate Interactions Using Scanning Tunneling Microscopy written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of a Scanning Probe Microscope and Studies of Graphene Grown on Copper by : Haider Imad Rasool
Download or read book Development of a Scanning Probe Microscope and Studies of Graphene Grown on Copper written by Haider Imad Rasool and published by . This book was released on 2012 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: A description of the construction of a low noise fiber interferometer deflection sensor is presented in order to illustrate the capabilities of the developed home built scanning probe microscope (SPM). A description of the critical components and a rationale behind their implementation in the design of the sensor is provided. An analysis of an ideal interference cavity is used to understand the optimization of the deflection sensor towards achieving the highest possible sensitivity and lowest deflection noise density. The low noise interferometer can be used to detect the motion of micron sized resonators without the need for external lenses or polarization sensitive optical components, allowing for simplified implementation in a variety of circumstances. True atomic resolution imaging of muscovite mica in water by atomic force microscopy (AFM) is demonstrated using the developed sensor in the home built SPM. Results on graphene grown on copper substrates by chemical vapor deposition (CVD) is provided. Graphene appears to grow over grains of different identities and across grain boundaries of the copper. Graphene island growth on the surface appears to depend on the underlying substrate. Temperature dependent growth studies show a significant decrease in growth rate with decreasing temperature. The graphene grown on copper is shown to be transferable to arbitrary substrates and can be suspended across perforations in a receiving substrate. The knowledge gained from the growths on copper allowed for the successful fabrication of a new type of hybrid polymeric - conductive AFM probe using patterned silicon substrates and thin copper films. Scanning tunneling microscopy (STM) was performed on graphene grown on copper substrates using the home built instrument. First, atomic scale STM imaging of graphene on polycrystalline copper substrates was accomplished. Graphene is shown to grow continuously over atomic steps, edges, and vertices of these corrugated copper surfaces. Continuous graphene growth is observed to exist over facets of different identities. The results on polycrystalline copper strongly suggests that the copper atoms are mobile during growth and that the underlying substrate does not limit graphene growth. In addition, STM was performed on graphene grown on copper (100) single crystals. The growth is again shown to be continuous over a wide range of surface features. The grown graphene exists in a variety of orientations with respect to the underlying copper crystal lattice. This leads to graphene overlayers which are polycrystalline in nature. Transmission electron microscopy (TEM) is used to reveal the crystallinity of graphene grown on single crystals and the real space distribution of the crystal domains in grown graphene. The compiled results of graphene growth on copper suggest that understanding and controlling the nucleation at the surface will ultimately be required for wafer scale growth of monolayer single crystal graphene on copper.
Book Synopsis Hot Scanning Tunneling Microscopy by : Christopher Andrew Pearson
Download or read book Hot Scanning Tunneling Microscopy written by Christopher Andrew Pearson and published by . This book was released on 1995 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Surfaces in Motion by : Mischa Sebastiaan Hoogeman
Download or read book Surfaces in Motion written by Mischa Sebastiaan Hoogeman and published by . This book was released on 1998 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
