Modification of Electronic Properties of Graphene with Self-Assembled Monolayers

Lee, B.; Chen, Y.; Duerr, Fabian; Mastrogiovanni, Daniel; Garfunkel, Eric; Andrei, Eva Y.; Podzorov, Vitaly

doi:10.1021/nl100587e

Cited by 108 publications

(137 citation statements)

References 17 publications

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“…Accessing these higher carrier densities appears to be within experimental reach, by biasing the gate at lower temperature (approximately 220 K, just above the freezing point of the ionic liquid) to prevent the occurrence of chemical reaction (whose rate decreases exponentially with lowering temperature) over a much broader gate voltage range (15,31). For applications, ionic gating allows to boost the conductivity of graphene, as it is required, for instance, for the practical realization of transparent electrodes in flat panel displays (6). (Indeed, it is believed that graphene has the potential to replace the commonly usedand expensive-indium tin oxide; note that the ionic liquids themselves are also transparent.)…”

Section: Fig 2 Electrical Properties Of Mono- Bi- and Trilayer Grmentioning

confidence: 99%

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Accessing the transport properties of graphene and its multilayers at high carrier density

Craciun

Koshino

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

303

264

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We present a comparative study of high carrier density transport in mono-, bi-, and trilayer graphene using electric double-layer transistors to continuously tune the carrier density up to values exceeding 10 14 cm −2 . Whereas in monolayer the conductivity saturates, in bi-and trilayer filling of the higher-energy bands is observed to cause a nonmonotonic behavior of the conductivity and a large increase in the quantum capacitance. These systematic trends not only show how the intrinsic high-density transport properties of graphene can be accessed by field effect, but also demonstrate the robustness of ion-gated graphene, which is crucial for possible future applications.T he investigation of transport through graphene layers has been focusing almost exclusively on the low carrier density regime (n ∼ 10 12 cm −2 ), where electrons behave as chiral particles and unexpected physical phenomena occur (1, 2). Despite exciting theoretical predictions (possible occurrence of superconductivity; refs. 3-5) and its clear relevance for technological applications (transparent electrodes for flat panel displays, ref. 6, supercapacitors, ref. 7, and biosensors, ref. 8), the high carrier density regime (n ∼ 10 14 cm −2 ) has remained vastly unexplored due to the limited amount of carrier density accessible in conventional solid-state field-effect transistors (9, 10). The recent development of so-called ionic-liquid gates, in which the coupling between gate electrode and transistor channel is effectively realized through moving ions that form an electric double layer (EDL) at the liquid/channel interface ( Fig. 1A), is now changing the situation. The gate voltage applied-up to several voltsdrops across a very large geometrical EDL capacitance of approximately 1-nm thick. As a result, the induced carrier density can easily exceed n 2D ≈ 10 14 cm −2 , more than one order of magnitude larger than that in conventional solid-state field-effect transistors (FETs). Such a very strong field effect is valuable for technological applications (for instance, in organic FETs, ref. 11, where it enables low-voltage operation) and as a versatile and effective tool to tune electronic states in a rich variety of systems (by modulating metal insulator transition, ref. 12, magnetoresistance, ref. 13, and by inducing superconductivity at the surface of insulators, refs. 14 and 15).Recent works show that ion gating can also be used in combination with graphene. Experiments (e.g., Raman spectroscopy, ref. 16, quantum capacitance, ref. 17, transport, refs. 18 and 19, etc.) have focused almost exclusively on properties of monolayer, but no characteristic high carrier density features in the transport properties were identified. Here, as an efficient strategy to reveal these characteristic features, we perform a comparative study of transport in ion-gated mono-, bi-, and trilayer graphene at high carrier density of approximately 10 14 cm −2 . The motivation for this strategy is twofold. First, when n 2D exceeds values of several 10 13 cm −2 , differ...

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Section: Fig 2 Electrical Properties Of Mono- Bi- and Trilayer Grmentioning

confidence: 99%

“…[3][4][5] and its clear relevance for technological applications (transparent electrodes for flat panel displays, ref. 6, supercapacitors, ref. 7, and biosensors, ref.…”

mentioning

confidence: 99%

Accessing the transport properties of graphene and its multilayers at high carrier density

Craciun

Koshino

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

303

264

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“…[16][17][18][19] However, the doping mechanism of chemical dopants is not yet fully understood and the relationship between charge density and carrier mobility is still under debate. [20][21][22] Furthermore, the adsorption of moisture and other chemical molecules after chemical treatment leads to a 40 % increase of the graphene sheet resistance within few days. 23,24 Consequently, an additional carefully chosen thin polymer coating is necessary to maintain its high conductivity without compromising its high transparency.…”

mentioning

confidence: 99%

Graphene–Ferroelectric Hybrid Structure for Flexible Transparent Electrodes

et al. 2012

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Graphene has exceptional optical, mechanical and electrical properties, making it an emerging material for novel optoelectronics, photonics and for flexible transparent electrode applications. However, the relatively high sheet resistance of graphene is a major constrain for many of these applications. Here we propose a new approach to achieve low sheet resistance in large-scale CVD monolayer graphene using non-volatile ferroelectric polymer gating. In this hybrid structure, large-scale graphene is heavily doped up to 3×10 13 cm -2 by non-volatile ferroelectric dipoles, yielding a low sheet resistance of 120 Ω/□ at ambient conditions. The graphene-ferroelectric transparent conductors (GFeTCs) exhibit more than 95 % transmittance from the visible to the near infrared range owing to the highly transparent nature of the ferroelectric polymer. Together with its excellent mechanical flexibility, chemical inertness and the simple fabrication process of ferroelectric polymers, the proposed GFeTCs represent a new route towards large-scale graphene based transparent electrodes and optoelectronics.KEYWORDS CVD graphene, ferroelectric polymer gating, sheet resistance, high transparency, mechanical flexibility, charged impurity scattering 2 Graphene keeps attracting much attention with enormous amount of experimental and theoretical activity, since its first micromechanical exfoliation in 2004. [1][2][3][4] As one atomic layer membrane, graphene is highly transparent (97.3 %) over a wide range of wavelengths from the visible to the near infrared (IR). 5Owing to its covalent carbon-carbon bonding, graphene is also one of the strongest materials with a remarkably high Young's modulus of ~ 1 TPa. 6 The combination of its high transparency, wideband tunability and excellent mechanical properties make graphene a very promising candidate for flexible electronics, optoelectronics and phonotics. 7-9The technical breakthrough of large-scale graphene synthesis has further accelerated the use of graphene films as transparent electrodes. 10,11To utilize graphene as transparent electrodes for applications such as solar cells 12 , organic light emitting diodes, 13 touch panels and displays 14, the key challenge is to reduce the sheet resistance to values comparable with indium tin oxide (ITO), which provides the best known combination of transparency (> 90 %) and sheet resistance (< 100 Ω/□). 8,15 Conventional methods to reduce the sheet resistance like electrostatic doping of graphene requires complex fabrication steps of dielectric deposition and gate electrode preparations, which are not practical for doping large-scale graphene and consume power to maintain the doping levels. 12,14 Chemical doping has been shown to effectively reduce the sheet resistance of graphene. [16][17][18][19] However, the doping mechanism of chemical dopants is not yet fully understood and the relationship between charge density and carrier mobility is still under debate. [20][21][22] Furthermore, the adsorption of moisture and other chemical molecul...

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“…19,20 Additionally, SAM modification of graphene also leads to electronic passivation of graphene edges and defects, thus might be responsible for a strong doping at the interface due to high acidity of the protons. 21 Although there have been various studies to enhance Schottky diodes depend on the graphene layers, researches on SAMs modification of silicon and graphene interface has been insufficient.In this study, n-type silicon substrates were modified by novel MePIFA and DPIFA SAM molecules to improve grafene/Si interface properties and increase charge carrier injection. Schottky diodes were fabricated by CVD grown graphene layers that were transferred onto bare and SAMs modified n-type silicon substrates.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Effect of Aromatic SAMs Molecules on Graphene/Silicon Schottky Diode Performance

Yağmurcukardeş

Aydın

Can

et al. 2016

ECS J. Solid State Sci. Technol.

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Au/n-Si/Graphene/Au Schottky diodes were fabricated by transferring atmospheric pressure chemical vapor deposited (APCVD) graphene on silicon substrates. Graphene/n-Si interface properties were improved by using 5-[(3-methylphenyl)(phenyl) amino]isophthalic acid (MePIFA) and 5-(diphenyl)amino]isophthalic acid (DPIFA) aromatic self-assembled monolayer (SAM) molecules. The surface morphologies of modified and non-modified films were investigated by atomic force microscopy and scanning electron microscopy. The surface potential characteristics were obtained by Kelvin-probe force microscopy and found as 0.158 V, 0.188 V and 0,383 V as a result of SAMs modification. The ideality factors of n-Si/Graphene, n-Si/MePIFA/Graphene and n-Si/DPIFA/Graphene diodes were found as 1.07, 1.13 and 1.15, respectively. Due to the chain length of aromatic organic MePIFA and DPIFA molecules, also the barrier height φ B values of the devices were decreased. While the barrier height of n-Si/Graphene diode was obtained as 0.931 eV, n-Si/MePIFA/Graphene and n-Si/DPIFA/Graphene diodes have barrier height of 0.820 and 0.720 eV, respectively. Graphene is a one-atom thick sheet of sp 2 bonded carbon atoms that are arranged in a honeycomb crystal lattice with exceptional properties. At room temperature electron mobility reached 2.5 × 10 5 cm 2 /V.s. 1 Young's modulus of 1 TPa and intrinsic strength of 130 GPa are very close to that were predicted by theory.2 Very high thermal conductivity (above 3000 WmK −1 ), 3 low optical absorption (∼2.3%), 4 ability to sustain high electric current densities 5 and be suitable to chemical functionalization [6][7][8] are other important properties of graphene that attract great attention. When graphene is transferred onto semiconductors such as GaAs, GaN, SiC and Si; it forms Schottky junctions.9-12 More efficient and stable solar cells and Schottky barrier devices will be achieved by the development of surface improvement, doping and functionalization. 13,14 The electrical transport performance of the fabricated Schottky diode is directly based on interface properties between substrate and graphene layer. 15Chemical Vapor Deposition (CVD) is promising technique for large area and high quality graphene growth. 16 In this technique, carbon precursors (methane, ethylene) are deposited carbon atoms onto the surfaces of various transition metals such as Nickel and Copper under high temperatures and form graphene. [16][17][18] Self-assembled monolayers (SAMs) are well-oriented molecular structures that are formed by the adsorption of an active surfactant on a substrate surface. Aromatic SAMs were used to modify anode/hole transport layer interface in order to achieve preferable barrier alignment and charge carrier injection. 19,20 Additionally, SAM modification of graphene also leads to electronic passivation of graphene edges and defects, thus might be responsible for a strong doping at the interface due to high acidity of the protons. 21 Although there have been various studies to enhance Schottky diodes depend...

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Modification of Electronic Properties of Graphene with Self-Assembled Monolayers

Cited by 108 publications

References 17 publications

Accessing the transport properties of graphene and its multilayers at high carrier density

Accessing the transport properties of graphene and its multilayers at high carrier density

Graphene–Ferroelectric Hybrid Structure for Flexible Transparent Electrodes

Effect of Aromatic SAMs Molecules on Graphene/Silicon Schottky Diode Performance

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