Search query: Modulating the electronic and magnetic properties of graphene

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abstract: Graphene, an sp2 hybridized single sheet of carbon atoms organized in a honeycomb lattice, is a zero band gap semiconductor or semimetal. This emerging material has been the subject of recent intensive research due to the novelty of its structural, electronic, optical, mechanical, and magnetic properties. Due to these properties, graphene is a favorable material for the fabrication of electronic devices, transparent electrodes, spintronics devices, and a growing array of several other applications that explore the potential of this marvelous material. However, the lack of intrinsic band gap and nonmagnetic nature of graphene limit its practical applications in the widely expanding field of carbon based devices. To take advantage of the hidden potential of this material, numerous techniques have been developed to tailor its electronic and magnetic properties. These methods include the mutual interaction between graphene layer and its substrate, doping with surface adatoms, substitutional doping, vacancy creation, and edges and strain manipulation. Herein, an overview of recently emerging innovative techniques adopted to tailor the electronic and magnetic properties of graphene is presented. The limitations, possible directions for future research and applications in diverse fields of these methods are also mentioned.
author_names: Salma Nigar

Zhongfu Zhou

Hao Wang

Muhammad Imtiaz
title: Modulating the electronic and magnetic properties of graphene
year: 2017

abstract: This article reviews the basic theoretical aspects of graphene, a one atom thick allotrope of carbon, with unusual two dimensional Dirac like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron electron and electron phonon interactions in single layer and multilayer graphene are also presented.
author_names: Antonio H Castro Neto

Francisco Guinea

Nuno M R Peres

Kostya S Novoselov

Andre K Geim
title: The electronic properties of graphene
year: 2009

abstract: Integrated optical modulators with high modulation speed, small footprint and large optical bandwidth are poised to be the enabling devices for on chip optical interconnects. Semiconductor modulators have therefore been heavily researched over the past few years. However, the device footprint of silicon based modulators is of the order of millimetres, owing to its weak electro optical properties. Germanium and compound semiconductors, on the other hand, face the major challenge of integration with existing silicon electronics and photonics platforms. Integrating silicon modulators with high quality factor optical resonators increases the modulation strength, but these devices suffer from intrinsic narrow bandwidth and require sophisticated optical design; they also have stringent fabrication requirements and limited temperature tolerances. Finding a complementary metal oxide semiconductor (CMOS) compatible material with adequate modulation speed and strength has therefore become a task of not only scientific interest, but also industrial importance. Here we experimentally demonstrate a broadband, high speed, waveguide integrated electroabsorption modulator based on monolayer graphene. By electrically tuning the Fermi level of the graphene sheet, we demonstrate modulation of the guided light at frequencies over 1 GHz, together with a broad operation spectrum that ranges from 1.35 to 1.6 um under ambient conditions. The high modulation efficiency of graphene results in an active device area of merely 25 um2, which is among the smallest to date. This graphene based optical modulation mechanism, with combined advantages of compact footprint, low operation voltage and ultrafast modulation speed across a broad range of wavelengths, can enable novel architectures for on chip optical communications.
author_names: Ming Liu

Xiaobo Yin

Erick Ulin-Avila

Baisong Geng

Thomas Zentgraf

Long Ju

Feng Wang

Xiang Zhang
title: A graphene based broadband optical modulator
venue: Nature
year: 2011

abstract: We describe the synthesis of bilayer graphene thin films deposited on insulating silicon carbide and report the characterization of their electronic band structure using angle resolved photoemission. By selectively adjusting the carrier concentration in each layer, changes in the Coulomb potential led to control of the gap between valence and conduction bands. This control over the band structure suggests the potential application of bilayer graphene to switching functions in atomic scale electronic devices.
author_names: Taisuke Ohta

Aaron Bostwick

Thomas Seyller

Karsten Horn

Eli Rotenberg
title: Controlling the Electronic Structure of Bilayer Graphene
venue: Science
year: 2006

abstract: Individual graphene oxide sheets subjected to chemical reduction were electrically characterized as a function of temperature and external electric fields. The fully reduced monolayers exhibited conductivities ranging between 0.05 and 2 S/cm and field effect mobilities of 2 200 cm2/Vs at room temperature. Temperature dependent electrical measurements and Raman spectroscopic investigations suggest that charge transport occurs via variable range hopping between intact graphene islands with sizes on the order of several nanometers. Furthermore, the comparative study of multilayered sheets revealed that the conductivity of the undermost layer is reduced by a factor of more than 2 as a consequence of the interaction with the Si/SiO2 substrate.
author_names: Cristina Gomez-Navarro

Ralf Thomas Weitz

Alexander M Bittner

Matteo Scolari

Alf Mews

Marko Burghard

Klaus Kern
title: Electronic transport properties of individual chemically reduced graphene oxide sheets.
venue: Nano letters
year: 2007

abstract: Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability to conduct heat. The room temperature thermal conductivity of carbon materials span an extraordinary large range of over five orders of magnitude from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. Here, I review the thermal properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. Special attention is given to the unusual size dependence of heat conduction in two dimensional crystals and, specifically, in graphene. I also describe the prospects of applications of graphene and carbon materials for thermal management of electronics.
author_names: Alexander A Balandin
title: Thermal properties of graphene and nanostructured carbon materials.
venue: Nature materials
year: 2011

abstract: Although graphite is known as one of the most chemically inert materials, we have found that graphene, a single atomic plane of graphite, can react with atomic hydrogen, which transforms this highly conductive zero overlap semimetal into an insulator. Transmission electron microscopy reveals that the obtained graphene derivative (graphane) is crystalline and retains the hexagonal lattice, but its period becomes markedly shorter than that of graphene. The reaction with hydrogen is reversible, so that the original metallic state, the lattice spacing, and even the quantum Hall effect can be restored by annealing. Our work illustrates the concept of graphene as a robust atomic scale scaffold on the basis of which new two dimensional crystals with designed electronic and other properties can be created by attaching other atoms and molecules.
author_names: Daniel C Elias

Rahul R Nair

T M G Mohiuddin

S V Morozov

Peter Blake

M P Halsall

Andrea C Ferrari

Danil W Boukhvalov

Mikhail I Katsnelson

Andre K Geim

Kostya S Novoselov
title: Control of Graphene's Properties by Reversible Hydrogenation: Evidence for Graphane
venue: Science
year: 2009

abstract: Graphene is in many respects a nanomaterial with unique properties. Here I discuss the electronic structure, transport and optical properties of graphene, and how these are utilized in exploratory electronic and optoelectronic devices. Some suggestions for needed advances are made.
author_names: Phaedon Avouris
title: Graphene: electronic and photonic properties and devices.
venue: Nano letters
year: 2010

abstract: Graphene, a two dimensional, single layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene based materials are discussed.
author_names: Xiao Huang

Zongyou Yin

Shixin Wu

Xiaoying Qi

Qiyuan He

Qichun Zhang

Qingyu Yan

Freddy Yin Chiang Boey

Hua Zhang
title: Graphene based materials: synthesis, characterization, properties, and applications.
venue: Small
year: 2011

abstract: There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them) from a materials science perspective.
author_names: Yanwu Zhu

Shanthi Murali

Weiwei Cai

Xuesong Li

Ji Won Suk

Jeffrey R Potts

Rodney S Ruoff
title: Graphene and graphene oxide: synthesis, properties, and applications.
venue: Advanced materials
year: 2010