Tuning the graphene work function by electric field effect.
TL;DR: In this paper, a variation of the work function for single and bilayer graphene devices measured by scanning Kelvin probe microscopy (SKPM) is reported, by using the electric field effect, which can be adjusted as the gate voltage tunes the Fermi level across the charge neutrality point.
Abstract: We report variation of the work function for single and bilayer graphene devices measured by scanning Kelvin probe microscopy (SKPM). By use of the electric field effect, the work function of graphene can be adjusted as the gate voltage tunes the Fermi level across the charge neutrality point. Upon biasing the device, the surface potential map obtained by SKPM provides a reliable way to measure the contact resistance of individual electrodes contacting graphene.
Citations
More filters
TL;DR: Approaches, Derivatives and Applications Vasilios Georgakilas,† Michal Otyepka,‡ Athanasios B. Bourlinos,† Vimlesh Chandra, Namdong Kim, K. Kim,§,⊥ Radek Zboril,*,‡ and Kwang S. Kim.
Abstract: Approaches, Derivatives and Applications Vasilios Georgakilas,† Michal Otyepka,‡ Athanasios B. Bourlinos,‡ Vimlesh Chandra, Namdong Kim, K. Christian Kemp, Pavel Hobza,‡,§,⊥ Radek Zboril,*,‡ and Kwang S. Kim* †Institute of Materials Science, NCSR “Demokritos”, Ag. Paraskevi Attikis, 15310 Athens, Greece ‡Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 12, 771 46 Olomouc, Czech Republic Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo naḿ. 2, 166 10 Prague 6, Czech Republic
3,460 citations
University of Cambridge1, Istituto Italiano di Tecnologia2, Lancaster University3, University of Manchester4, Catalan Institution for Research and Advanced Studies5, Technical University of Denmark6, Nokia7, Queen Mary University of London8, University of Trento9, fondazione bruno kessler10, Technische Universität München11, Polytechnic University of Milan12, Centre national de la recherche scientifique13, University of Trieste14, University of Ioannina15, University of Geneva16, Trinity College, Dublin17, Texas Instruments18, University of Paris19, Spanish National Research Council20, Leiden University21, Delft University of Technology22, University of Patras23, École Normale Supérieure24, Radboud University Nijmegen25, Nest Labs26, Airbus UK27, Seoul National University28, Yonsei University29, University of Oxford30, Chalmers University of Technology31, University of Groningen32, STMicroelectronics33, Chemnitz University of Technology34, Max Planck Society35, Aalto University36
TL;DR: An overview of the key aspects of graphene and related materials, ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries are provided.
Abstract: We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
2,560 citations
TL;DR: The magnetite-graphene hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem.
Abstract: Magnetite−graphene hybrids have been synthesized via a chemical reaction with a magnetite particle size of ∼10 nm. The composites are superparamagnetic at room temperature and can be separated by an external magnetic field. As compared to bare magnetite particles, the hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem. Their high binding capacity is due to the increased adsorption sites in the M−RGO composite which occurs by reducing the aggregation of bare magnetite. Since the composites show near complete (over 99.9%) arsenic removal within 1 ppb, they are practically usable for arsenic separation from water.
1,806 citations
TL;DR: It is shown that for a graphene-silicon interface, Fermi-level pinning can be overcome and a triode-type device with a variable barrier, a “barristor,” can be made and used to create devices such as inverters.
Abstract: Despite several years of research into graphene electronics, sufficient on/off current ratio I(on)/I(off) in graphene transistors with conventional device structures has been impossible to obtain. We report on a three-terminal active device, a graphene variable-barrier "barristor" (GB), in which the key is an atomically sharp interface between graphene and hydrogenated silicon. Large modulation on the device current (on/off ratio of 10(5)) is achieved by adjusting the gate voltage to control the graphene-silicon Schottky barrier. The absence of Fermi-level pinning at the interface allows the barrier's height to be tuned to 0.2 electron volt by adjusting graphene's work function, which results in large shifts of diode threshold voltages. Fabricating GBs on respective 150-mm wafers and combining complementary p- and n-type GBs, we demonstrate inverter and half-adder logic circuits.
921 citations
TL;DR: In this article, the authors combine the unique electronic properties of semiconducting monolayer MoS2 with the high conductivity of graphene to build a 2D heterostructure capable of information storage.
Abstract: Memory cells are an important building block of digital electronics We combine here the unique electronic properties of semiconducting monolayer MoS2 with the high conductivity of graphene to build a 2D heterostructure capable of information storage MoS2 acts as a channel in an intimate contact with graphene electrodes in a field-effect transistor geometry Our prototypical all-2D transistor is further integrated with a multilayer graphene charge trapping layer into a device that can be operated as a nonvolatile memory cell Because of its band gap and 2D nature, monolayer MoS2 is highly sensitive to the presence of charges in the charge trapping layer, resulting in a factor of 10(4) difference between memory program and erase states The two-dimensional nature of both the contact and the channel can be harnessed for the fabrication of flexible nanoelectronic devices with large-scale integration
889 citations
References
More filters
TL;DR: By using micromechanical cleavage, a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides are prepared and studied.
Abstract: We report free-standing atomic crystals that are strictly 2D and can be viewed as individual atomic planes pulled out of bulk crystals or as unrolled single-wall nanotubes. By using micromechanical cleavage, we have prepared and studied a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides. These atomically thin sheets (essentially gigantic 2D molecules unprotected from the immediate environment) are stable under ambient conditions, exhibit high crystal quality, and are continuous on a macroscopic scale.
10,586 citations
TL;DR: The direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers is reported, and two different methods of patterning the films and transferring them to arbitrary substrates are presented, implying that the quality of graphene grown by chemical vapours is as high as mechanically cleaved graphene.
Abstract: Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of approximately 280 Omega per square, with approximately 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm(2) V(-1) s(-1) and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.
10,033 citations
TL;DR: It is shown that the opacity of suspended graphene is defined solely by the fine structure constant, a = e2/hc � 1/137 (where c is the speed of light), the parameter that describes coupling between light and relativistic electrons and that is traditionally associated with quantum electrodynamics rather than materials science.
Abstract: There are few phenomena in condensed matter physics that are defined only by the fundamental constants and do not depend on material parameters. Examples are the resistivity quantum, h/e2 (h is Planck's constant and e the electron charge), that appears in a variety of transport experiments and the magnetic flux quantum, h/e, playing an important role in the physics of superconductivity. By and large, sophisticated facilities and special measurement conditions are required to observe any of these phenomena. We show that the opacity of suspended graphene is defined solely by the fine structure constant, a = e2/hc feminine 1/137 (where c is the speed of light), the parameter that describes coupling between light and relativistic electrons and that is traditionally associated with quantum electrodynamics rather than materials science. Despite being only one atom thick, graphene is found to absorb a significant (pa = 2.3%) fraction of incident white light, a consequence of graphene's unique electronic structure.
7,952 citations
TL;DR: In this paper, a single layer graphene was suspended ∼150nm above a Si/SiO2 gate electrode and electrical contacts to the graphene was achieved by a combination of electron beam lithography and etching.
7,276 citations
TL;DR: The transparency, conductivity, and ambipolar transfer characteristics of the films suggest their potential as another materials candidate for electronics and opto-electronic applications.
Abstract: In this work we present a low cost and scalable technique, via ambient pressure chemical vapor deposition (CVD) on polycrystalline Ni films, to fabricate large area (∼cm2) films of single- to few-layer graphene and to transfer the films to nonspecific substrates. These films consist of regions of 1 to ∼12 graphene layers. Single- or bilayer regions can be up to 20 μm in lateral size. The films are continuous over the entire area and can be patterned lithographically or by prepatterning the underlying Ni film. The transparency, conductivity, and ambipolar transfer characteristics of the films suggest their potential as another materials candidate for electronics and opto-electronic applications.
5,663 citations