Electrochemical doping of graphene with toluene

Kaverzin, Alexey; Strawbridge, Sharon M.; Price, Adam S.; Withers, Freddie; Savchenko, A. K.; Horsell, D. W.

doi:10.1016/j.carbon.2011.05.017

Cited by 33 publications

(33 citation statements)

References 26 publications

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“…Therefore, in the case the reaction or diffusion rates are slower than the rate of change of gate voltage electrochemical doping can lead to hysteresis effects which are often observed in graphene-based FET devices [21–24]. …”

Section: Reviewmentioning

confidence: 99%

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Electronic and electrochemical doping of graphene by surface adsorbates

Pinto

Markevich

2014

Beilstein J. Nanotechnol.

114

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SummaryMany potential applications of graphene require its precise and controllable doping with charge carriers. Being a two-dimensional material graphene is extremely sensitive to surface adsorbates, so its electronic properties can be effectively modified by deposition of different atoms and molecules. In this paper, we review two mechanisms of graphene doping by surface adsorbates, namely electronic and electrochemical doping. Although, electronic doping has been extensively studied and discussed in the literature, much less attention has been paid to electrochemical doping. This mechanism can, however, explain the doping of graphene by adsorbates for which no charge transfer is expected within the electronic doping model. In addition, electrochemical doping is in the origin of the hysteresis effects often observed in graphene-based field effect transistors when operating in the atmospheric environment.

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Section: Reviewmentioning

confidence: 99%

“…7, results in n-type doping [24,39–40]. However, doping of graphene in the presence of water and toluene cannot be understood within the electronic model.…”

Section: Reviewmentioning

confidence: 99%

Electronic and electrochemical doping of graphene by surface adsorbates

Pinto

Markevich

2014

Beilstein J. Nanotechnol.

114

View full text Add to dashboard Cite

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“…29 and 30 are not subjected to nonuniform strain. 31 However, the application of the present theory to such experiments, as well as the study of the interplay with other neutral currents, is beyond the scope of this work and will be explored elsewhere. 32 The rest of the article is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Valley Hall effect and nonlocal transport in strained graphene

2017

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Graphene subject to high levels of shear strain leads to strong pseudo-magnetic fields resulting in the emergence of Landau levels. Here we show that, with modest levels of strain, graphene can also sustain a classical valley hall effect (VHE) that can be detected in nonlocal transport measurements. We provide a theory of the strain-induced VHE starting from the quantum Boltzmann equation. This allows us to show that, averaging over short-range impurity configurations destroys quantum coherence between valleys, leaving the elastic scattering time and inter-valley scattering rate as the only parameters characterizing the transport theory. Using the theory, we compute the nonlocal resistance of a Hall bar device in the diffusive regime. Our theory is also relevant for the study of moderate strain effects in the (nonlocal) transport properties of other two-dimensional materials and van der Walls heterostructures.

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“…This has led to graphene being used as the active element in a range of sensing applications [10]. Studies of changes to these properties have led to an understanding of the orientation of adsorbed molecular species [11], chemical activity mediated by the surface [12], and the type of electron scattering caused [13]. Adsorbed gases have also been shown to affect the THz conductivity of graphene [14].…”

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confidence: 99%

Optically induced oxygen desorption from graphene measured using femtosecond two-pulse correlation

et al. 2014

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Recently, there has been a great deal of interest in the effect of atmospheric gases on the properties of graphene. We investigate the electrical and optical response of graphene-based field effect transistors that have been exposed to high purity oxygen gas using a combination of ultrafast two-pulse correlation (to give high temporal resolution) and low-frequency transport measurements (to monitor the photoinduced changes in the Fermi level). By measuring the Fermi level shifts, we are only sensitive to the oxygen atoms that interact directly with the surface. We compare our results to predictions of the empirical friction model for molecular desorption. We show the time scale of the relaxation associated with oxygen desorption to be ∼100 fs, suggesting the desorption proceeds through hot electron generation in the graphene rather than heating of the lattice through hot phonon generation. Ultrafast laser measurements on graphene have afforded great insight into quasiparticle relaxation mechanisms and lifetimes in this material [1][2][3][4]. For example, it is now known that, after ultrafast photoexcitation of the electrons, energy relaxation occurs through mechanisms with markedly different time scales: first through energy redistribution by electron-electron scattering (∼10 fs), then thermalization with optical phonons (∼100 fs), and finally, anharmonic decay of optical phonons and/or coupling to substrate phonons (∼1 ps) [2][3][4]. More recently, ultrafast laser measurements have been used to probe the time scales of charge transfer to graphene from photoexcited adsorbed molecules [5]. However, experimentally the exact time scales and mechanisms associated with the adsorption and desorption of molecular species are not well known [6].Molecules that interact with graphene can significantly influence its electrical, optical, and mechanical properties [7][8][9]. This has led to graphene being used as the active element in a range of sensing applications [10]. Studies of changes to these properties have led to an understanding of the orientation of adsorbed molecular species [11], chemical activity mediated by the surface [12], and the type of electron scattering caused [13]. Adsorbed gases have also been shown to affect the THz conductivity of graphene [14]. Of particular interest is the interaction of graphene with molecular oxygen. Oxygen molecules can adsorb onto the surface of a pristine graphene sheet resulting in fractional charge transfer from the graphene to the oxygen. Recent studies have shown the importance of the substrate and environmental conditions to this charge transfer [15,16]. However, the nature of the interaction with oxygen has yet to be fully explored, and it is unclear exactly how and where the oxygen molecules bind to graphene and how efficiently molecules can dissociate at these sites.Here, we investigate the mechanisms, energies, and time scales relevant for the molecular adsorption of oxygen molecules on graphene. To do this, we have designed an experiment which permits high electrica...

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Electrochemical doping of graphene with toluene

Cited by 33 publications

References 26 publications

Electronic and electrochemical doping of graphene by surface adsorbates

Electronic and electrochemical doping of graphene by surface adsorbates

Valley Hall effect and nonlocal transport in strained graphene

Optically induced oxygen desorption from graphene measured using femtosecond two-pulse correlation

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