Ultraflat graphene

Lui, Chun Hung; Liu, Li; Mak, Kin Fai; Flynn, George W.; Heinz, Tony F.

doi:10.1038/nature08569

Cited by 646 publications

(535 citation statements)

References 27 publications

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“…Therefore, there is a need to provide approaches for removal of these disorders. Typically, the intrinsic ripples may be suppressed by depositing graphene on atomically smooth substrates [323]. Wrinkles can be reduced by increasing the thickness of nickel substrate at the growth step, soaking PMMA/graphene film in deionized water before transfer [194], and transferring graphene to hydrophobic substrates [319].…”

Section: Disorders In Graphene Structurementioning

confidence: 99%

Structure of graphene and its disorders: a review

Gao

Lee

et al. 2018

Science and Technology of Advanced Materials

487

187

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Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.

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Section: Disorders In Graphene Structurementioning

confidence: 99%

Structure of graphene and its disorders: a review

Gao

Lee

et al. 2018

Science and Technology of Advanced Materials

487

187

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“…An estimation of maximum height variation shows reasonable agreement with topographic data of AFM. 15 We show that the typical electronic structure of graphene remains unperturbed being in contact with the mica surface, which plays an important role in practical applications of graphene. The possible influence of the mica substrate on transport properties of graphene is also addressed.…”

Section: Introductionmentioning

confidence: 99%

“…17 These properties make this material a favorable candidate as a substrate for the deposition of graphene in potential graphene-based devices. Although experimental studies propose a strong interfacial binding between graphene and mica resulting from the vdW interaction, 15,18 the nature of such a binding has not been unambiguously established. Details of the binding, such as dependence on the surface morphology, are also unclear.…”

Section: Introductionmentioning

confidence: 99%

“…Quite recently it was reported that the intensity of such ripples can be strongly dependent on the substrate on which graphene is deposited. 15 In particular, graphene monolayers display an exceedingly flat structure being placed on a mica surface, which is several times smoother than a SiO 2 surface. This observation means that the ripples, independently on their nature, can be strongly suppressed by interfacial interactions between graphene and an appropriately chosen (flat) substrate.…”

Section: Introductionmentioning

confidence: 99%

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Graphene adhesion on mica: Role of surface morphology

et al. 2011

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We investigate theoretically the adhesion and electronic properties of graphene on a muscovite mica surface using the density functional theory (DFT) with van der Waals (vdW) interactions taken into account (the vdW-DF approach). We found that irregularities in the local structure of cleaved mica surface provide different mechanisms for the mica-graphene binding. By assuming electroneutrality for both surfaces, the binding is mainly of vdW nature, barely exceeding thermal energy per carbon atom at room temperature. In contrast, if potassium atoms are non uniformly distributed on mica, the different regions of the surface give rise to n-or p-type doping of graphene. In turn, an additional interaction arises between the surfaces, significantly increasing the adhesion. For each case the electronic states of graphene remain unaltered by the adhesion. It is expected, however, that the Fermi level of graphene supported on realistic mica could be shifted relative to the Dirac point due to asymmetry in the charge doping. Obtained variations of the distance between graphene and mica for different regions of the surface are found to be consistent with recent atomic force microscopy experiments. A relative flatness of mica and the absence of interlayer covalent bonding in the mica-graphene system make this pair a promising candidate for practical use.

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“…An AFM image demonstrating the thickness of different layer numbers of graphene is shown in Figure 2(d). However, the AFM measurement is not very accurate, depending on the substrate used [43], and the line scanning work mode determine the low throughput of AFM. To sum up, searching graphene under optical microscope, followed by checking in Raman spectroscope, is highly recommended to surely confirm whether the target sample is a single-layer graphene or not.…”

Section: Methods To Obtain Graphenementioning

confidence: 99%

Graphene-based ambipolar electronics for radio frequency applications

2012

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Graphene is considered as a promising material to construct field-effect transistors (FETs) for high frequency electronic applications due to its unique structure and properties, mainly including extremely high carrier mobility and saturation velocity, the ultimate thinnest body and stability. Through continuously scaling down the gate length and optimizing the structure, the cut-off frequency of graphene FET (GFET) was rapidly increased and up to about 300 GHz, and further improvements are also expected. Because of the lack of an intrinsic band gap, the GFETs present typical ambipolar transfer characteristic without off state, which means GFETs are suitable for analog electronics rather than digital applications. Taking advantage of the ambipolar characteristic, GFET is demonstrated as an excellent building block for ambipolar electronic circuits, and has been used in applications such as highperformance frequency doublers, radio frequency mixers, digital modulators, and phase detectors. Owing to the success isolation of single layer graphene by Novoselov et al. [4] in 2004, the obsolete point was broken down and a tremendous research field has been expanded based on the 2D material [5][6][7][8][9][10][11], and even the 2010 Nobel Prize in Physics was awarded jointly to A. K. Geim and K. S. Novoselov "for groundbreaking experiments regarding the two-dimensional material graphene" [12,13]. The special 2D structure of graphene provides a series of unique properties in mechanics, thermology, optics, and electronics [10,11,[14][15][16][17][18][19]. Graphene not only provides an experimental platform for basic physics, such as relativistic quantum mechanics (or quantum electrodynamics), which is due to the *Corresponding authors (email: zyzhang@pku.edu.cn; lmpeng@pku.edu.cn) massless property of the Dirac fermion behaved electrons in graphene [20][21][22], but also manifests promising application potential in numerous application fields, such as analog radio frequency (RF) field-effect transistors (FETs) [10,[23][24][25], flexible transparent electrodes and touch screen [26], photodetection [11,27,28], and spin transport [29,30]. In this review article, we will focus on the graphene based electronics and applications, especially RF performance of graphene and ambipolar electronics.

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Ultraflat graphene

Cited by 646 publications

References 27 publications

Structure of graphene and its disorders: a review

Structure of graphene and its disorders: a review

Graphene adhesion on mica: Role of surface morphology

Graphene-based ambipolar electronics for radio frequency applications

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