NEW PROGRESS ON GRAPHENE RESEARCH Edited by Jian Ru Gong New Progress on Graphene Research http://dx.doi.org/10.5772/3358 Edited by Jian Ru Gong Contributors Alexander Feher, Eugen Syrkin, Sergey Feodosyev, Igor Gospodarev, Kirill Kravchenko, Fei Zhuge, Miroslav Pardy, Tong Guo-Ping, Victor Zalipaev, Michael Forrester, Dariush Jahani, Tao Tu, Wenge Zheng, Bin Shen, Wentao Zhai, Mineo Hiramatsu Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2013 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Dejan Grgur Technical Editor InTech DTP team Cover InTech Design team First published March, 2013 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechopen.com New Progress on Graphene Research, Edited by Jian Ru Gong p. cm. ISBN 978-953-51-1091-0 free online editions of InTech Books and Journals can be found at www.intechopen.com Contents Preface VII Section 1 Theoretical Aspect 1 Chapter 1 Electronic Tunneling in Graphene 3 Dariush Jahani Chapter 2 Localised States of Fabry-Perot Type in Graphene Nano-Ribbons 29 V. V. Zalipaev, D. M. Forrester, C. M. Linton and F. V. Kusmartsev Chapter 3 Electronic Properties of Deformed Graphene Nanoribbons 81 Guo-Ping Tong Chapter 4 The Cherenkov Effect in Graphene-Like Structures 101 Miroslav Pardy Chapter 5 Electronic and Vibrational Properties of Adsorbed and Embedded Graphene and Bigraphene with Defects 135 Alexander Feher, Eugen Syrkin, Sergey Feodosyev, Igor Gospodarev, Elena Manzhelii, Alexander Kotlar and Kirill Kravchenko Section 2 Experimental Aspect 159 Chapter 6 Quantum Transport in Graphene Quantum Dots 161 Hai-Ou Li, Tao Tu, Gang Cao, Lin-Jun Wang, Guang-Can Guo and Guo-Ping Guo Chapter 7 Advances in Resistive Switching Memories Based on Graphene Oxide 185 Fei Zhuge, Bing Fu and Hongtao Cao Chapter 8 Surface Functionalization of Graphene with Polymers for Enhanced Properties 207 Wenge Zheng, Bin Shen and Wentao Zhai Chapter 9 Graphene Nanowalls 235 Mineo Hiramatsu, Hiroki Kondo and Masaru Hori ContentsVI Preface Graphene is a one-atom-thick and two-dimensional repetitive hexagonal lattice sp 2 -hybri‐ dized carbon layer. The extended honeycomb network of graphene is the basic building block of other important allotropes of carbon. 2D graphene can be wrapped to form 0D full‐ erenes, rolled to form 1D carbon nanotubes, and stacked to form 3D graphite. Depending on its unique structure, graphene yields many excellent electrical, thermal, and mechanical properties. It has been interesting to both theoreticians and experimentalists in various fields, such as materials, chemistry, physics, electronics, and biomedicine, and great prog‐ ress have been made in this rapid developing arena. The aim of publishing this book is to present the recent new achievements about graphene research on a variety of topics. And the book is divided into two parts: Part I, from theoreti‐ cal aspect, Graphene tunneling (Chapter 1), Localized states of Fabry-Perot type in graphene nanoribbons (Chapter 2), Electronic properties of deformed graphene nanoribbons (Chapter 3), The Čererenkov effect in graphene-like structures (Chapter 4), and Electronic and vibra‐ tional properties of adsorbed and embedded carbon nanofilms with defects (Chapter 5) are elaborated; Part II, from experimental aspect, Quantum transport in graphene quantum dots (Chapter 6), Advances in resistive switching memories based on graphene oxide (Chapter 7), Surface functionalization of graphene with polymers for enhanced properties (Chapter 8), and Carbon nanowalls: synthesis and applications (Chapter 9) are introduced. Also, in- depth discussions ranging from comprehensive understanding to challenges and perspec‐ tives are included for the respective topic. Each chapter is relatively independent of others, and the Table of Contents we hope will help readers quickly find topics of interest without necessarily having to go through the whole book. Last, I appreciate the outstanding contributions from scientists with excellent academic re‐ cords, who are at the top of their fields on the cutting edge of technology, to the book. Research related to graphene updates every day, so it is impossible to embody all the progress in this collection, and hopefully it could be of any help to people who are interested in this field. Prof. Jian Ru Gong National Center for Nanoscience and Technology, Beijing P. R. China Section 1 Theoretical Aspect [...]... velocity are parallel 12 New Progress on Graphene Research 10 Graphene - Research and Applications Figure 3 an one dimensional schematic view of a n-p-n junction of gapless graphene In all three zones the energy bands are linear in momentum and therefore we have massless electrons passing through the barrier By applying the continuity conditions of the wave functions at the two discontinuities of the barrier... important to know that resonances occur when a p-n interface is in series with an n-p interface, forming a p-n-p or n-p-n junction 22 New Progress on Graphene Research 20 Graphene - Research and Applications 7 Transmission into spatial regions of finite mass In this section the transmission of massless electrons into some regions where the corresponding energy dispersion relation is not linear any more... (58) 16 New Progress on Graphene Research 14 Graphene - Research and Applications as those of massless Dirac fermions in graphene Now that we have found the corresponding eigenfunctions of Hamiltonian (4.52), assuming an electron incident upon a step of height V0 , we can write the single valley Hamiltonian as: H = v F σ.p + ∆σz + V (r), (59) where V (r) = 0 for region I (x < 0) and for the region II... nano-electronic opportunities for graphene requires a mass gap in it’s energy spectrum just like a conventional semiconductor In fact the lack of a bandgap on graphene, can limit graphene s uses in electronics because if there is no gaps in graphene spectrum one can’t turn off a graphene- made transistor In this section, motivated by mass production of graphene, we obtain the exact expression for transmission... phase is not considered This means that considering the 4 There is no need to say that when there is no electrostatic potential q x is positive 26 New Progress on Graphene Research 24 Graphene - Research and Applications Figure 8 left: Transmission probability as a functions of incident angle for an electron of energy E = 85meV, D = 100nm and V0 = 200meV Right: Transmission in gapped graphene for gap... the third region we have only a transmitted wave and therefore the wave function in this region is: t ψI I I = √ 2 α λγeiφ ei (k x x +k y y) (79) With the continuity of the spinors at the discontinuities, we arrive at the following set of equations: α + αr = βa + βb (80) λγeiφ − λγre−iφ = ηλ′ aeiθt − ηλ′ be−iθt (81) 20 New Progress on Graphene Research 18 Graphene - Research and Applications βaeiqx D... case of massless electrons tunneling in graphene, we concern ourselves to evaluation of transmission probability of an electron incident upon a potential barrier with height much higher than the electron’s energy 2.1 Tunneling of an electron with energy lower than the electrostatic potential For calculating the transmission probability of an electron incident from the left on a potential barrier of hight... regions in graphene One of the methods for inducing these gaps in energy spectra of graphene is to grow it on top of a hexagonal boron nitride with the B-N distance very close to C-C distance of graphene [8,9,10] One other method is to pattern graphene nanoribbons.[11,12] In this method graphene planes are patterned such that in several areas of the graphene flake narrow nanoribbons may exist Here, considering... consider the following potential:  0 x < 0 V ( x ) = V0 0 < x < w  0 x>w (2) For regions I, the solution of Schrodinger’s equation will be a combination of incident and reflected plane waves while in region II, depending on the energy, the solution will be either a plane wave or a decaying exponential form ψ I = eikx + re−ikx (3) ψ I I = aeiqx + be−iqx (4) ψ I I I = teikx (5) 6 4 New Progress on Graphene. .. junction of graphene which could be realized with a backgate and could correspond to a potential step of hight V0 on which an massless electron of energy E is incident ( see Fig 2) is considered Two region, therefore, can be considered The region for which x < 0 corresponding to a kinetic energy of E and the region corresponding to a kinetic energy of E − V0 In order to obtain the transmission and . NEW PROGRESS ON GRAPHENE RESEARCH Edited by Jian Ru Gong New Progress on Graphene Research http://dx.doi.org/10.5772/3358 Edited by Jian Ru Gong Contributors Alexander Feher,. (9) New Progress on Graphene Research6 Electronic Tunneling in Graphene 5 10.5772/51980 Figure 2. A p-n junction of graphene in which massless electrons incident upon an electrostatic region with. incidence contrary to the case of tunneling of massless Dirac fermions in gapless graphene which leads to the total transparency of the barrier New Progress on Graphene Research4 Electronic Tunneling