Electrical Characteristics of Bernal Stacked (A-B) Graphene Bilayer PDF Download
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Author: Kayoung Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 106
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Book Description
Graphene bilayers in Bernal stacking exhibit a transverse electric (E) field dependent band gap, thanks to the on-site electron energy asymmetry between the two layers, which can be used to increase the channel resistivity, and enable higher on/off ratio devices. Using dual-gated device structure, we investigate the transport characteristics of exfoliated graphene bilayers as a function of carrier density and E-field at temperature from 295 K down to 0.3 K. At high E-field, strong conduction suppression near the charge neutrality point is observed, a primary characteristic introduced by band gap opening. The conductivity suppression persists up to the finite threshold voltages, which increase with increasing the E-field, similar to a gapped semiconductor. We extract the transport gap as a function of E-field from the threshold measurement, and further discuss the impact of disorder. At gate bias higher than the threshold, conductivity increases linearly as carrier density increases, which contrasts to the sub-linear dependence in graphene monolayer. Mobility shows decreasing tendency with the increasing E-field, which changes little as temperature changes. Besides, we probe the electrical characteristics of quasi-free-standing graphene bilayers grown on SiC at temperature down to 0.3 K, based on the study on the exfoliated graphene bilayers. The epitaxial graphene bilayer on SiC is prepared by atmospheric pressure graphitization in Ar, followed by H2 intercalation, which renders the material quasi-free-standing. At the charge neutrality point, the longitudinal resistance shows an insulating behavior, and follows a temperature dependence consistent with variable range hopping transport in a gapped state. Besides, clear linear dependence of the conductivity on the carrier density is observed, which is distinguishable from the sub-linear dependence in graphene monolayer. These properties show that the epitaxial graphene bilayer grown on the SiC exhibits band-gap opening and Bernal stacked arrangement.
Author: Kayoung Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 106
Get Book Here
Book Description
Graphene bilayers in Bernal stacking exhibit a transverse electric (E) field dependent band gap, thanks to the on-site electron energy asymmetry between the two layers, which can be used to increase the channel resistivity, and enable higher on/off ratio devices. Using dual-gated device structure, we investigate the transport characteristics of exfoliated graphene bilayers as a function of carrier density and E-field at temperature from 295 K down to 0.3 K. At high E-field, strong conduction suppression near the charge neutrality point is observed, a primary characteristic introduced by band gap opening. The conductivity suppression persists up to the finite threshold voltages, which increase with increasing the E-field, similar to a gapped semiconductor. We extract the transport gap as a function of E-field from the threshold measurement, and further discuss the impact of disorder. At gate bias higher than the threshold, conductivity increases linearly as carrier density increases, which contrasts to the sub-linear dependence in graphene monolayer. Mobility shows decreasing tendency with the increasing E-field, which changes little as temperature changes. Besides, we probe the electrical characteristics of quasi-free-standing graphene bilayers grown on SiC at temperature down to 0.3 K, based on the study on the exfoliated graphene bilayers. The epitaxial graphene bilayer on SiC is prepared by atmospheric pressure graphitization in Ar, followed by H2 intercalation, which renders the material quasi-free-standing. At the charge neutrality point, the longitudinal resistance shows an insulating behavior, and follows a temperature dependence consistent with variable range hopping transport in a gapped state. Besides, clear linear dependence of the conductivity on the carrier density is observed, which is distinguishable from the sub-linear dependence in graphene monolayer. These properties show that the epitaxial graphene bilayer grown on the SiC exhibits band-gap opening and Bernal stacked arrangement.
Author: Kikuji Hirose
Publisher: World Scientific
ISBN: 1860945120
Category : Science
Languages : en
Pages : 265
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Book Description
With cutting-edge materials and minute electronic devices being produced by the latest nanoscale fabrication technology, it is essential for scientists and engineers to rely on first-principles (ab initio) calculation methods to fully understand the electronic configurations and transport properties of nanostructures. It is now imperative to introduce practical and tractable calculation methods that accurately describe the physics in nanostructures suspended between electrodes.This timely volume addresses novel methods for calculating electronic transport properties using real-space formalisms free from geometrical restrictions. The book comprises two parts: The first details the basic formalism of the real-space finite-difference method and its applications. This provides the theoretical foundation for the second part of the book, which presents the methods for calculating the properties of electronic transport through nanostructures sandwiched by semi-infinite electrodes.
Author: Yuan Cao (S.M.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
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Book Description
Graphene is a two-dimensional material with exotic electronic, optical and mechanical properties. By stacking two layers of graphene together with a small rotation angle between them, a superlattice of arbitrarily large size can be formed. The hybridization of the electronic states in the two layers can result in reduced Fermi velocity, van Hove singularities and a gapped band structure. In this work, a novel tear-and-stack technique is developed to reliably produce twisted bilayer graphene with controlled angle, and electronic transport measurements of the resulting high-quality samples are performed and discussed. We discover novel insulating states that purely results from the moiŕe superlattice band structure. The magnetotransport properties of these insulating states are studied and indicate that these states have different structure with those in either graphene or AB-stacked bilayer graphene; it shows a non-monotonous change of Fermi surface area which agrees with theoretical calculations. The results point toward a new pathway for graphene-related physics and material research.
Author: Samuel David Littlejohn
Publisher: Springer Science & Business Media
ISBN: 3319007416
Category : Science
Languages : en
Pages : 172
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Book Description
This thesis examines a novel class of flexible electronic material with great potential for use in the construction of stretchable amplifiers and memory elements. Most remarkably the composite material produces spontaneous oscillations that increase in frequency when pressure is applied to it. In this way, the material mimics the excitatory response of pressure-sensing neurons in the human skin. The composites, formed of silicone and graphitic nanoparticles, were prepared in several allotropic forms and functionalized with naphthalene diimide molecules. A systematic study is presented of the negative differential resistance (NDR) region of the current-voltage curves, which is responsible for the material’s active properties. This study was conducted as a function of temperature, graphite filling fraction, scaling to reveal the break-up of the samples into electric field domains at the onset of the NDR region, and an electric-field induced metal-insulator transition in graphite nanoparticles. The effect of molecular functionalization on the miscibility threshold and the current-voltage curves is demonstrated. Room-temperature and low-temperature measurements were performed on these composite films under strains using a remote-controlled, custom-made step motor bench.
Author: Mahmood Aliofkhazraei
Publisher: CRC Press
ISBN: 1466591323
Category : Science
Languages : en
Pages : 719
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Book Description
Discover the Unique Electron Transport Properties 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 cells, and s
Author: Marcin Mucha-Kruczyński
Publisher: Springer Science & Business Media
ISBN: 3642309364
Category : Science
Languages : en
Pages : 90
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Book Description
This thesis presents the theory of three key elements of optical spectroscopy of the electronic excitations in bilayer graphene: angle-resolved photoemission spectroscopy (ARPES), visible range Raman spectroscopy, and far-infrared (FIR) magneto-spectroscopy. Bilayer graphene (BLG) is an atomic two-dimensional crystal consisting of two honeycomb monolayers of carbon, arranged according to Bernal stacking. The unperturbed BLG has a unique band structure, which features chiral states of electrons with a characteristic Berry phase of 2$\pi$, and it has versatile properties which can be controlled by an externally applied transverse electric field and strain. It is shown in this work how ARPES of BLG can be used to obtain direct information about the chirality of electron states in the crystal. The author goes on to describe the influence of the interlayer asymmetry, which opens a gap in BLG, on ARPES and on FIR spectra in a strong magnetic field. Finally, he presents a comprehensive theory of inelastic Raman scattering resulting in the electron-hole excitations in bilayer graphene, at zero and quantizing magnetic fields. This predicts their polarization properties and peculiar selection rules in terms of the inter-Landau-level transitions.
Author: Ming-fa Lin
Publisher: World Scientific
ISBN: 981127780X
Category : Science
Languages : en
Pages : 445
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Book Description
This comprehensive book delves into the fascinating world of quasiparticle properties of graphene-related materials. The authors thoroughly explore the intricate effects of intrinsic and extrinsic interactions on the material's properties, while unifying the single-particle and many-particle properties through the development of a theoretical framework. The book covers a wide range of research topics, including long-range Coulomb interactions, dynamic charge density waves, Friedel oscillations and plasmon excitations, as well as optical reflection and transmission spectra of thin films. Also it highlights the crucial roles of inelastic Coulomb scattering and optical scattering in the quasiparticle properties of layered systems, and the impact of crystal symmetry, number of layers, and stacking configuration on their uniqueness. Furthermore, the authors explore the topological properties of quasiparticles, including 2D time-reversal-symmetry protected topological insulators with quantum spin Hall effect, and rhombohedral graphite with Dirac nodal lines. Meanwhile, the book examines the gate potential application for creating topological localized states and shows topological invariants of 2D Dirac fermions, and binary Z2 topological invariants under chiral symmetry. The calculated results are consistent with the present experimental observations, establishing it as a valuable resource for individuals interested in the quasiparticle properties of novel materials.
Author: Chiun-Yan Lin
Publisher: CRC Press
ISBN: 1351334964
Category : Science
Languages : en
Pages : 124
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Book Description
This book provides an overview of electronic and optical properties of graphite-related systems. It presents a well-developed and up-to-date theoretical model and addresses important advances in essential properties and diverse quantization phenomena. Key features include various Hamiltonian models, dimension-enriched carbon-related systems, complete and unusual results, detailed comparisons with the experimental measurements, clear physical pictures, and further generalizations to other emergent 2D materials. It also covers potential applications, such as touch-screen panel devices, FETs, supercapacitors, sensors, LEDs, solar cells, photodetectors, and photomodulators.
Author: Alain Diebold
Publisher: Springer Nature
ISBN: 3030803236
Category : Technology & Engineering
Languages : en
Pages : 495
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Book Description
This book covers the optical and electrical properties of nanoscale materials with an emphasis on how new and unique material properties result from the special nature of their electronic band structure. Beginning with a review of the optical and solid state physics needed for understanding optical and electrical properties, the book then introduces the electronic band structure of solids and discusses the effect of spin orbit coupling on the valence band, which is critical for understanding the optical properties of most nanoscale materials. Excitonic effects and excitons are also presented along with their effect on optical absorption. 2D materials, such as graphene and transition metal dichalcogenides, are host to unique electrical properties resulting from the electronic band structure. This book devotes significant attention to the optical and electrical properties of 2D and topological materials with an emphasis on optical measurements, electrical characterization of carrier transport, and a discussion of the electronic band structures using a tight binding approach. This book succinctly compiles useful fundamental and practical information from one of the fastest growing research topics in materials science and is thus an essential compendium for both students and researchers in this rapidly moving field.
Author: Devin Artan Cela
Publisher:
ISBN:
Category :
Languages : en
Pages : 76
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Book Description
Graphene is a single 2-dimensional atomic layer of hexagonally packed carbon atoms. Graphene has a unique combination of thermal, mechanical, and electronic properties, making it a useful tool for learning new physics as well as a material with high potential for applications. Bilayer graphene (2LG) and trilayer graphene (3LG) share many of the interesting properties of its monolayer relative, but with several key differences. This thesis makes use of resonant Raman spectroscopy to characterize these systems and quantify their layer number as well as stacking order in different graphene flakes. Three distinct graphitic systems were studied: bilayer graphene with Bernal stacking, and trilayer graphene with both Bernal and rhombohedral stacking. A number of back-gated bilayer and trilayer graphene devices were created via the method of mechanical exfoliation. The type of stacking and number of layers was confirmed using resonant Raman spectroscopy. Electron beam lithography was used in combination with a positive PMMA resist in order to pattern samples. Metal was then evaporated onto samples to create electrical contacts for use in gated measurements. These samples, along with my procedure, will be used for future measurement by members of the Dresselhaus research group. These gated graphene devices will be used with gate-modulated resonant Raman spectroscopy (GMMRS) in order to explore the electron-phonon properties of AB 2LG, ABA 3LG, and ABC 3LG graphene.
