Atomic Structure of Graphene on SiO<sub>2</sub>

Ishigami, Masa; Chen, Jianhao; Cullen, William; Fuhrer, Michael S.; Williams, Ellen D.

doi:10.1021/nl070613a

Cited by 1,449 publications

(1,477 citation statements)

References 27 publications

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“…[12] Indeed, in more recent studies, inert electrical responses (i.e., no response) for gaseous NH 3 were observed by annealing the exfoliated graphene at high temperature (400 °C) in Ar/H 2 atmosphere to remove possible polymer contaminations and produce atomically clean graphene sheets. [178] This inert sensing behavior of the cleaned graphene sensors is robust even upon the exposure to NH 3 vapor at a concentration of 1000 ppm (Fig. 5c) [11] and to dimethylmethylphosphonate (DMMP) vapor at a concentration of 100 ppm (Fig.…”

Section: Gfet Gas and Ion Sensorsmentioning

confidence: 93%

Sensing at the Surface of Graphene Field‐Effect Transistors

et al. 2016

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Abstract. 10Recent research trends now offer new opportunities for developing the next generations of label-free biochemical sensors using graphene and other two-dimensional materials. While the physics of graphene transistors operated in electrolyte is well grounded, important chemical challenges still remain to be addressed, namely the impact of the chemical functionalizations of graphene on the key electrical parameters and the sensing performances. In fact, graphene -at least ideal graphene -is highly chemically inert. The 15 functionalizations and chemical alterations of the graphene surface -both covalently and non-covalently -are crucial steps that define the sensitivity of graphene. The presence, reactivity, adsorption of gas and ions, proteins, DNA, cells and tissues on graphene have been successfully monitored with graphene. This review aims to unify most of the work done so far on biochemical sensing at the surface of a (chemically functionalized) graphene field-effect transistor and the challenges that lie ahead. We are convinced that graphene biochemical sensors 20 hold great promises to meet the ever-increasing demand for sensitivity, especially looking at the recent progresses suggesting that the obstacle of Debye screening can be overcome.2

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Section: Gfet Gas and Ion Sensorsmentioning

confidence: 93%

Sensing at the Surface of Graphene Field‐Effect Transistors

et al. 2016

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“…nanoelectronic devices). The graphene corrugations observed by a novel combined SEM/AFM/STM technique are suggested to be attributed to the partial conformation of the graphene to the SiO 2 , not to the intrinsic corrugations of graphene [316]. Besides, species like H 2 O may be trapped at the graphene/SiO 2 interface [317,318].…”

Section: Disorders In Graphene Structurementioning

confidence: 99%

“…The line defects (or GBs) are expected to be avoid by controlling the nucleation of graphene grains using seeded growth, and to synthesize spatially ordered arrays of graphene grains with pre-determined locations [78]. Lastly, cleaning of transferred graphene surface can be efficiently done by annealing in a clean or reducing environment such as vacuum, H 2 /N 2 or H 2 /Ar [316,324,325]. …”

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

447

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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“…Next we placed the sample in a vacuum chamber, and under continuous pumping we observed the Fermi level to gradually move toward the Dirac point. 35,36 Finally, after vacuum pumping for 2 days, the Dirac point voltage moved to a value < +20 V, as the turquoise line shows.In conclusion, we have studied the transmission properties of large-area graphene films in the THz and IR range. By applying an external gate voltage, we were able to electrically tune the Fermi level of graphene, which in turn modulated the transmission of THz and IR waves.…”

mentioning

confidence: 96%

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confidence: 96%

Terahertz and Infrared Spectroscopy of Gated Large-Area Graphene

Zhang²,

et al. 2012

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We have fabricated a centimeter-size single-layer graphene device, with a gate electrode, which can modulate the transmission of terahertz and infrared waves. Using time-domain terahertz spectroscopy and Fourier-transform infrared spectroscopy in a wide frequency range (10-10000 cm -1 ), we measured the dynamic conductivity change induced by electrical gating and thermal annealing.Both methods were able to effectively tune the Fermi energy, E F , which in turn modified the Drude-like intraband absorption in the terahertz as well as the '2E F onset' for interband absorption in the midinfrared. These results not only provide fundamental insight into the electromagnetic response of Dirac fermions in graphene but also demonstrate the key functionalities of large-area graphene devices that are desired for components in terahertz and infrared optoelectronics. KEYWORDS: graphene, Fermi level, terahertz dynamics, infrared spectroscopyThe AC dynamics of Dirac fermions in graphene have attracted much recent attention. The influence of linear dispersions, two-dimensionality, electron-electron interactions, and disorder on the dynamic conductivity, σ(ω), has been theoretically investigated, 1-11 whereas unique terahertz (THz) and mid-infrared (MIR) properties have been identified for novel optoelectronic applications. 12-17 For example, it has been predicted that the response of Dirac fermions to an applied AC electric field of frequency ω would automatically contain all odd harmonics of (2n+1)ω, where n is an integer, implying extremely high nonlinearity. 13,14 Furthermore, creation of electrons and holes through interband optical pumping is expected to lead to population inversion near the Dirac point, resulting in negative σ(ω), or gain, in the THz to MIR range. 12,17 While initial experimental investigations on graphene have concentrated on DC characteristics, these recent theoretical studies have instigated a flurry of new experimental activities to uncover unusual AC properties. A number of experiments have already confirmed the so-called universal optical conductivity σ 0 = e 2 /4 ! (e: electronic charge and ! : reduced Planck constant) for interband transitions in a wide spectral range. [18][19][20][21] On the other hand, experimental studies of the intraband conductivity have been very limited, [21][22][23][24] Here, we describe our THz and MIR spectroscopy study of large-area (centimeter scale), single-layer graphene with an electrically tunable Fermi level. In a field-effect transistor configuration consisting of graphene on a SiO 2 /p-Si substrate, the transmitted intensity of THz and MIR electromagnetic waves was observed to change with the gate voltage. The Drude-like intraband conductivities and the '2E F onset' of the interband transitions, monitored through time-domain THz spectroscopy (TDTS) and Fourier-transform IR (FTIR) spectroscopy, respectively, were both modulated by the gate voltage. By analyzing the spectral shape of the induced changes with appropriate models, we were able to determine ...

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Atomic Structure of Graphene on SiO₂

Cited by 1,449 publications

References 27 publications

Sensing at the Surface of Graphene Field‐Effect Transistors

Sensing at the Surface of Graphene Field‐Effect Transistors

Structure of graphene and its disorders: a review

Terahertz and Infrared Spectroscopy of Gated Large-Area Graphene

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Atomic Structure of Graphene on SiO2

Cited by 1,449 publications

References 27 publications

Sensing at the Surface of Graphene Field‐Effect Transistors

Sensing at the Surface of Graphene Field‐Effect Transistors

Structure of graphene and its disorders: a review

Terahertz and Infrared Spectroscopy of Gated Large-Area Graphene

Contact Info

Product

Resources

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Atomic Structure of Graphene on SiO₂