Recent progress in fabrication techniques of graphene nanoribbons wentao xu and taewoo lee graphene has been the focus of research since its isolation in 2004. The different selection rules for optical transitions in graphene nanoribbons with armchair and zigzag edges were reported. Analytical study of electronic structure in armchair graphene. However, the lack of a bandgap restricts its application in semiconductor industry in spite of its predicted extremely high carrier mobility 4250000 cm2 v 1s. Graphene nanoribbons gnrs, also called nano graphene ribbons or nanographite ribbons are strips of graphene with width less than 50 nm. When graphene is in the form of narrow sheet less than 50 nanometers wide, its called a graphene strip, a nanoribbon or nanostripe.
Based on the translational invariance, we choose plane wave basis along the xdirection. These results were supplemented by a comparative study of zigzag nanoribbons with single wall armchair carbon nanotubes by hsu and. The derivation originates from energy dispersion throughout the entire brillouin zone of uniaxial. Electron tunneling current in an npn bipolar transistor. The one dimension counterpart of graphene is the nanoribbon, simply the strips of a graphene. The graphene nanoribbons in the arrays are formed using a scalable, bottomup, chemical vapor deposition cvd technique in which the 001 facet of the germanium is used to orient the graphene nanoribbon crystals along the. We demonstrate that such nanoribbon always has a gap in. Color online examples of energy bands for a graphene nanoribbon with periodic boundary conditions in one direction.
The d band raman intensity is calculated for armchair edged graphene nanoribbons using an extended tightbinding method in which the effect of interactions up to the seventh nearest neighbor is. Magnetism in dehydrogenated armchair graphene nanoribbon. Labelfree sensors capable of detecting low concentrations of significant biomolecular substances without inducing immune response would simplify experiments, minimize errors, improve realtime. We investigate the electronic transport properties of a graphene nanoribbon heterojunction constructed by fusing a zigzag and an armchair graphene nanoribbon zgnragnr side by side. The d band raman intensity is calculated for armchair edged graphene nanoribbons using an extended tightbinding method in which the effect of interactions up to the seventh nearest neighbor is taken into account. Utilizing firstprinciples theory, we demonstrate that halfmetallicity can be realized in a junction composed of nonmagnetic armchair graphene nanoribbon agnr and ferromagnetic ni electrodes. Low temperature and temperaturedependent measurements reveal a length. A uniaxial tensile test in the armchair direction refers to the. Pdf we investigate the electronic band structure of an undoped graphene armchair nanoribbon.
Firstprinciples insilico design and characterization abstract. Device performance of 10 nm length armchair graphene nanoribbon field effect transistors with 1. A number of research groups 20,21 have derived the analytical wave function and energy dispersion of zigzag nanoribbon. Savelev,2,3 and franco nori2,4 1institute for theoretical and applied electrodynamics, russian academy of sciences, 125412, moscow, russia 2advanced science institute, the institute of physical and chemical research riken, wakoshi, saitama, 3510198, japan 3department of physics, loughborough university. Modulation of electronic structure of armchair mos2 nanoribbon long zhang, langhui wan, yunjin yu, bin wang, fuming xu, yadong wei, and yang zhao college of physics science and technology, and institute of computational condensed matter physics, shenzhen university, shenzhen 518060, peoples republic of china school of materials science and engineering, nanyang. Here, we introduce a novel approach to access the frontier states of armchair graphene nanoribbons agnrs. A systematic investigation is performed on the electronic transport properties of armchair graphene nanoribbon agnr heterojunctions using spinpolarized density functional theory calculations in combination with the nonequilibrium greens function formalism.
Electronic transport in graphene nanoribbons melinda young han this dissertation examines the electronic properties of lithographically fabricated graphene anoribbons gnrs with widths in the tens of nanometers. Spintronic transport in armchair graphene nanoribbon with. How do zigzag and armchair graphene nanoribbons differ. Electronic transport across a junction between armchair graphene nanotube and zigzag nanoribbon transmission in an armchair nanotube without a zigzag halfline of dimers basant lal sharmaa department of mechanical engineering, indian institute of technology kanpur, kanpur, u. Depending on its edge morphology, the grapheme nanoribbons are of two types zigzag graphene nanoribbon zgnr and armchair graphene nanoribbon agnr. Simulation of dirac electron tunneling current in armchair. The primitive lattice vectors are denoted by a and b. Sullivan, and yuan ping feng electron transmission modes in electricall y biased graphene nanoribbons. If a graphene nanoribbon runs in the armchair direction, that is, if the long edge of a ribbon shows an armchair pattern, then it is referred to as as an armchair. Below a critical electric field strength, the charge transport in these materials is governed by the quasiparticle mechanism. Electronic structure of oxygen functionalized armchair graphene.
Electronic transport in graphene nanoribbons kim group at harvard. This demonstration shows the electronic structure of both armchair and zigzag graphene nanoribbons obtained by diagonalization of the tightbinding tb hamiltonian matrix in the sampled 1d brillouin zone. Armchair edge armchair edge zigzag edge a b 3a 0 4 n l a a b b a a 0 4 n l fig. D band raman intensity calculation in armchair edged graphene. The carboncarbon bond length in graphene is about 0. Controllable spindependent transport in armchair graphene nanoribbon structures. The complex band structure for armchair graphene nanoribbons. The electronic transport properties of a graphene nanoribbon gnr are known to be sensitive to its width, edges and defects. The device is made of ptype and ntype semiconductor. The earliest numerical results on the optical properties of graphene nanoribbons were obtained by lin and shyu in 2000.
Graphene armchair graphene nanoribbon chemical adsorption lithium adsorption on two dimensional graphene and armchair graphene nanoribbons is studied using advanced density functional theory calculations. Top and bottom are zigzag edges, left and right are armchair edges. Pdf controllable spindependent transport in armchair. Tunneling current of electron in armchair graphene.
Jul 24, 2019 graphene nanoribbons are 2d hexagonal lattices with semiconducting band gaps. There are two primary ways to cut out such a nanoribbon, and these two structures are known as armchair or zigzag nanoribbons figure2. Allarmchair graphene nanoribbon fieldeffect uridine. Modulation of electronic structure of armchair mos nanoribbon. Armchair graphene nanoribbons with different proportions of edge oxygen atoms. Electronic properties of armchair graphene nanoribbons. Koskinen 1nanoscience center, department of physics, university of jyv. Armchair a and zigzag z type graphene nanoribbons gnr have been investigated for its suitability to sense the toxic h 2 s gas, by using density functional theory dft based abinitio approach. Comparison of fracture behavior of defective armchair and. Analytical study of electronic structure in armchair. We simulate quantum mechanical tunneling current in armchair graphene nanoribbon tunnel fieldeffect transistors agnrtfets. The iv model is enhanced by integrating both linear and saturation regions into a unified and precise model of agnrs. Request pdf on dec 1, 2018, nazmul amin and others published phonondephasing in armchair graphene nanoribbon find, read and cite all the research you need on researchgate. Unified drain current model of armchair graphene nanoribbons.
Perfect armchair graphene nanoribbon the structure of armchair gnrs consists two types of sublattices a and b as illustrated in fig. Structure of armchair and zigzag nanoribbons since gnrs are stripes of. By using firstprinciples calculations, we find that. Electrical conductivity of doped armchair graphene. In density of states, many quasi0d and quasi1d type states are found to be induced in addition to dominant 1d states. Structural and electronic properties of armchair graphene. Us9287359b1 oriented bottomup growth of armchair graphene. Double vacancy defects were introduced in each graphene nanoribbon at its center or at. Electronic transport through zigzagarmchair graphene.
Electronic properties of armchair graphene nanoribbons a. In the forcecontrol method, the forces are applied on the edge atoms as shown in the. The tb hamiltonian matrix depends on the value of the nearestneighbor hopping parameter for electrons, which is about 2. Graphene is the basic structural element of some carbon allotropes including graphite charcoal carbon nanotubes fullerence chemical structures. We use a transfer matrix method tmm to calculate the electron transmittance and the dirac electron tunneling. There are many forms of graphene nanoribbon gnr, but the armchair conformation is one the most studied because of their zeroband gap and high charge carrier mobility. The earliest theoretical studies of graphene nanoribbons, using a simple tightbinding method, predicted that of the armchair nanoribbons, whose width index satisfies is an integer, are metallic, and another are semiconductor with band gaps depending on their width, while all zigzag nanoribbons are metallic, a similar behavior as carbon nanotubes cnts. Since gnrs are stripes of graphene, edge atoms are not saturated. The d band intensity is shown to be independent of the nanoribbon. Researchers produce graphene nanoribbons with perfect. Graphene based electronic devices are promising for future application. Allarmchair graphene nanoribbon fieldeffect uridine diphosphate glucose sensor.
Graphenebased electronic devices are promising for future application. Graphene nanoribbons gnrs are a new class of materials that have promising applications in nextgeneration nanoelectronic and optoelectronic. Ultranarrow heterojunctions of armchairgraphene nanoribbons. Graphene is a oneatomiclayer thick twodimensional material made of carbon atoms arranged in a honeycomb structure. Analysis of graphene nanoribbons passivated with gold. Depending on the direction of the ribbon axis, graphene nanoribbons have an armchair edge orange or a zigzag edge blue. Based on its edgeshape and width, graphene can be metallic or semiconducting 5, 6. The relative stability of different adsorption sites is investigated taking into account different ribbon widths, adsorbate densities, and.
The size effect in a graphene nanoribbon manifests itself, first of all, through sensitivity of its properties to the nanoribbon width. Graphene nanoribbons gnrs, narrow and straightedged stripes of graphene, attract a great deal of attention because of their excellent electronic and magnetic properties. Using a tight binding transfer matrix method, we calculate the complex band structure of armchair graphene nanoribbons. Low temperature and temperaturedependent measurements reveal a length and orientation. Ultranarrow metallic armchair graphene nanoribbons. Results show that the effect of vacancies in zigzag graphene nanoribbon is more profound than in armchair graphene nanoribbon. Introducing f impurity in armchair graphene nanoribbon agnr is.
Graphene nanoribbons are available in two forms or orientations. Oct, 2016 utilizing firstprinciples theory, we demonstrate that halfmetallicity can be realized in a junction composed of nonmagnetic armchair graphene nanoribbon agnr and ferromagnetic ni electrodes. The relativistic dirac equation is used to determine electron wave functions in the agnrs, while the potential profile is solved by the poisson equation. The quasiparticles involved in the process, known as polarons and bipolarons, are selfinteracting states between the system charges and local lattice distortions. Its fascinating electrical, optical, and mechanical properties ignited enormous interdisciplinary interest from the physics, chemistry, and materials science fields. Twisting graphene nanoribbons into carbon nanotubes. D band raman intensity calculation in armchair edged. A systematic investigation is performed on the electronic transport properties of armchairgraphene nanoribbon agnr heterojunctions using spinpolarized density functional theory calculations in combination with the nonequilibrium greens function formalism. Engineering the band gap of armchair graphene nanoribbons. Binding energy for hcpd and pdcpd structures represent characteristic drops with the increasing graphene nanoribbon width.
The halfmetallic property originates from the agnr energy gap of the up spin located at the fermi energy, while large electronic states are generated for the down spin. A unified currentvoltage iv model of uniaxial strained armchair graphene nanoribbons agnrs incorporating quantum confinement effects is presented in this paper. Scalable and precise synthesis of armchairedge graphene. A graphene nanoribbon with armchair edges and zigzag edges. Graphene nanoribbons are 2d hexagonal lattices with semiconducting band gaps. Electronic band structure of armchair and zigzag graphene. We report electronic structure and electricfield modulation calculations in the width direction for armchair graphene nanoribbons acgnrs using a. According to the geometry of their edge, in their simplest forms, they can be either armchair agnrs or zigzag zgnrs, although more complicated gnrs with irregular edges are also possible. The electronic properties of graphene nanoribbons grown on metal substrates are significantly masked by the ones of the supporting metal surface. The tunneling current is calculated for various variables such as baseemitter voltage, basecurrent voltage, and agnr width.
Graphene can be transformed from a semimetal into a semiconductor if it is confined into nanoribbons narrower than 10 nm with controlled crystallographic orientation and. Stability conditions of armchair graphene nanoribbon. We report the synthesis of an armchair graphene nanoribbon with a width of nine carbon atoms on au111 through surfaceassisted. Color onlinethe lattice structure of a graphene sheet. Researchers produce graphene nanoribbons with perfect zigzag. Analysis of graphene nanoribbons passivated with gold, copper. Tunneling current of electron in armchair graphene nanoribbon. Based on the translational invariance, we choose plane wave basis along the. The interaction of armchair graphene nanoribbons agnr with f has. Savelev,2,3 and franco nori2,4 1institute for theoretical and applied electrodynamics, russian academy of sciences, 125412, moscow, russia 2advanced science institute, the institute of physical and chemical research riken, wakoshi, saitama, 3510198, japan.
Theoretical investigation on armchair graphene nanoribbons. Using the e ectivemass approximation 2224, the analytical forms of electronic wave functions of armchair graphene nanoribbons within the lowenergy range have been found. Zigzag graphene nanoribbon zgnr has metal properties while armchair graphene nanoribbon agnr can be metal or semiconductor. Armchair graphene nanoribbon molecular wires carbon 76, 285 2014. Electronic transport in graphene nanoribbons melinda young han this dissertation examines the electronic properties of lithographically fabricated graphene \nanoribbons gnrs with widths in the tens of nanometers. Firstprinciple studies of armchair graphene nanoribbons iopscience. The characteristic of npn bipolar junction transistor based on silicon 7 and graphene material was modeled 8,9. Aug 10, 2015 graphene can be transformed from a semimetal into a semiconductor if it is confined into nanoribbons narrower than 10 nm with controlled crystallographic orientation and welldefined armchair edges. Although the zigzag graphene nanoribbon attracts scientific interest because of its magnetic properties, the study of the magnetism of the armchair graphene nanoribbons agnrs is insufficient. This effect is evidently associated with the edge effect, because the nanoribbon width is directly related to. Also, the effect of double vacancy defect on the ultimate failure stress is greater in zigzag graphene nanoribbons than in armchair graphene nanoribbon due to bond orientation with respect.
Ultranarrow metallic armchair graphene nanoribbons nature. Phonondephasing in armchair graphene nanoribbon request pdf. On adsorption of h 2 s, the variations in original metallic behaviour of zgnr and semiconducting behaviour of agnr has further been analysed by observing the conductance and bandgap variation as a. Dft analysis of h2s adsorbed zigzag and armchair graphene. Graphene is a semiconductor when prepared as an ultranarrow ribbon although the material is actually a conductive material.
Graphene ribbons were introduced as a theoretical model by mitsutaka fujita and coauthors to examine the edge and nanoscale size effect in graphene. We investigate the electronic transport properties of a graphene nanoribbon heterojunction constructed by fusing a zigzag and an armchair graphene nanoribbon zgnragnr side. For the graphene nanoribbons with all oxygen atoms on the edges, both band. Graphene nanoribbon arrays, methods of growing graphene nanoribbon arrays and electronic and photonic devices incorporating the graphene nanoribbon arrays are provided. Atoms enclosed in the vertical horizontal rectangle. Firstprinciples calculations of pdterminated symmetrical. Electronic transport across a junction between armchair. Halfmetallic properties hongmei liu1,2, hisashi kondo2 and takahisa ohno2,3 abstract utilizing firstprinciples theory, we demonstrate that halfmetallicity can be realized in a junction composed of nonmagnetic armchair graphene nanoribbon agnr and ferromagnetic ni electrodes. Jan 31, 2019 allarmchair graphene nanoribbon fieldeffect uridine diphosphate glucose sensor.
Airywavefunction approach is employed to obtain electron transmittance, and the obtained transmittance is then used to obtain the tunneling current. In this article, by using the first principle calculations based on the density functional theory, we present a detailed investigation of the energy band and. Highlights pdtermination significantly influence the electronic properties of armchair graphene nanoribbons, and induce metallicity. Pdf electronic properties of armchair graphene nanoribbons. Mar 24, 2016 pattern template for graphene nanoribbons. As of yet, there is no fabrication method for gnrs to satisfy both precision at the atomic scale and scalability, which is critical for fundamental research and future technological development. Lithium adsorption on armchair graphene nanoribbons. Revealing the electronic structure of silicon intercalated.
Graphene nanoribbons gnrs are a new class of materials that have promising applications in nextgeneration nanoelectronic and optoelectronic devices 1,2,3. Graphene is the basic structural element of some carbon allotropes including graphite charcoal. The derivation originates from energy dispersion throughout the entire brillouin zone of uniaxial strained agnrs. The graphene nanoribbons in the arrays are formed using a scalable, bottomup, 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. Size and chirality dependent elastic properties of. Recent progress in fabrication techniques of graphene nanoribbons. Direct oriented growth of armchair graphene nanoribbons on. Both armchair graphene nanoribbons agnrs and zigzag graphene nanoribbons. The unit cell contains natype atoms and nbtype atoms. Onsurface synthesis and characterization of 9atom wide. Pdf on mar 22, 2011, erjun kan and others published graphene nanoribbons. Dec 14, 2015 graphene nanoribbons gnrs are a new class of materials that have promising applications in nextgeneration nanoelectronic and optoelectronic devices 1,2,3. Graphene nanoribbons gnrs are nanometerwide stripes of carbon atoms arranged in a honeycomb lattice.
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