Impact of Vacancies on Diffusive and Pseudodiffusive Electronic Transport in Graphene

Cresti, Alessandro; Louvet, Thibaud; Ortmann, Frank; Tuan, Dinh Van; Lenarczyk, Pawel; Huhs, Georg; Roche, Stephan

doi:10.3390/cryst3020289

Cited by 33 publications

(11 citation statements)

References 34 publications

(44 reference statements)

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“…Those persistent peaks are originating from strongly localized states, most probably located close to the cut edges, similarly to what was observed for vacancies in graphene 60 . Such Actually for high cut angle and long cut lengths, σ yy (E, L) displays a decreasing behavior synonym of localization effects.…”

Section: Electronic Structuressupporting

confidence: 71%

Thermal and electronic transport characteristics of highly stretchable graphene kirigami

et al. 2017

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For centuries, cutting and folding papers with special patterns have been used to build beautiful, flexible and complex three-dimensional structures. Inspired by the old idea of kirigami (paper cutting), and the outstanding properties of graphene, recently graphene kirigami structures were fabricated to enhance the stretchability of graphene. However, the possibility of further tuning the electronic and thermal transport along the 2D kirigami structures has remained original to investigate. We therefore performed extensive atomistic simulations to explore the electronic, heat and load transfer along various graphene kirigami structures. The mechanical response and thermal transport were explored using classical molecular dynamics simulations. We then used a real-space Kubo-Greenwood formalism to investigate the charge transport characteristics in graphene kirigami. Our results reveal that graphene kirigami structures present highly anisotropic thermal and electrical transport. Interestingly, we show the possibility of tuning the thermal conductivity of graphene by four orders of magnitude. Moreover, we discuss the engineering of kirigami patterns to further enhance their stretchability by more than 10 times as compared with pristine graphene. Our study not only provides a general understanding concerning the engineering of electronic, thermal and mechanical response of graphene, but more importantly can also be useful to guide future studies with respect to the synthesis of other 2D material kirigami structures, to reach highly flexible and stretchable nanostructures with finely tunable electronic and thermal properties.

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Section: Electronic Structuressupporting

confidence: 71%

Thermal and electronic transport characteristics of highly stretchable graphene kirigami

et al. 2017

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“…These results suggest that low temperature transport measurements could help with detecting the presence of a magnetic state in weakly hydrogenated graphene. Several experimental techniques pointed towards the possible occurrence of a metal-insulator transition in hydrogenated graphene, as a function of hydrogenation [30,31]. These results have been interpreted in terms of the crossover between different quantum transport regimes, triggered by hydrogenation-induced disorder [32,33].…”

Section: Introductionmentioning

confidence: 94%

“…Thus, the predictions of the LKMC process simulator are directly linked to the predictions of the electronic properties of the HG systems. We note that quantum transport in disordered, including hydrogenated, graphene has been the subject of thorough theoretical analysis (see, e.g., [27][28][29][30][31][32][33][34][35]). However, the impact of the H configurations, as they would emerge from the fabrication processes, on the transport features of the H-G samples has been a less studied topic.…”

Section: Quantum Conductance Of Hydrogenated Graphenementioning

confidence: 99%

Role of H Distribution on Coherent Quantum Transport of Electrons in Hydrogenated Graphene

et al. 2017

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Using quantum mechanical methods, in the framework of non-equilibrium Green's function (NEGF) theory, we discuss the effects of the real space distribution of hydrogen adatoms on the electronic properties of graphene. Advanced methods for the stochastic process simulation at the atomic resolution are applied to generate system configurations in agreement with the experimental realization of these systems as a function of the process parameters (e.g., temperature and hydrogen flux). We show how these Monte Carlo (MC) methods can achieve accurate predictions of the functionalization kinetics in multiple time and length scales. The ingredients of the overall numerical methodology are highlighted: the ab initio study of the stability of key configurations, on lattice matching of the energetic configuration relation, accelerated algorithms, sequential coupling with the NEGF based on calibrated Hamiltonians and statistical analysis of the transport characteristics. We demonstrate the benefit to this coupled MC-NEGF method in the study of quantum effects in manipulated nanosystems.

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“…The Dirac conductivity peak is a signature of the highly localized nature of zero-energy states generated by uncompensated vacancies [16], which are not enough spatially extended to significantly contribute to tunneling and obviate to the DOS decrease. More details on the energy gap scaling and, in general, on the transport properties away from the Dirac point will be published elsewhere [49].…”

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confidence: 99%

Broken Symmetries, Zero-Energy Modes, and Quantum Transport in Disordered Graphene: From Supermetallic to Insulating Regimes

et al. 2013

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The role of defect-induced zero-energy modes on charge transport in graphene is investigated using Kubo and Landauer transport calculations. By tuning the density of random distributions of monovacancies either equally populating the two sublattices or exclusively located on a single sublattice, all conduction regimes are covered from direct tunneling through evanescent modes to mesoscopic transport in bulk disordered graphene. Depending on the transport measurement geometry, defect density, and broken sublattice-symmetry, the Dirac point conductivity is either exceptionally robust against disorder (supermetallic state) or suppressed through a gap opening or by algebraic localization of zero-energy modes, whereas weak localization and the Anderson insulating regime are obtained for higher energies. These findings clarify the contribution of zero-energy modes to transport at the Dirac point, hitherto controversial.The electronic transport properties of graphene are known to be very peculiar with unprecedented manifestations of quantum phenomena such as Klein tunneling [1, 2], weak antilocalization [3,4], or the anomalous quantum Hall effect [5,6], all driven by a π-Berry phase stemming from graphene sublattice symmetry and pseudospin degree of freedom [7][8][9]. These fascinating properties, yielding high charge mobility [10,11], are robust as long as disorder preserves a long range character. The fundamental nature of transport precisely at the Dirac point is, however, currently a subject of fierce debate and controversies. Indeed, for graphene deposited on oxide substrates, the nature of low-energy transport physics (as its sensitivity to weak disorder) is masked by the formation of electron-hole puddles [9]. A remarkable experiment has, however, recently demonstrated the possibility to screen out these detrimental effects [12], providing access to the zero-energy Dirac physics. An unexpectedly large increase of the resistivity at the Dirac point was tentatively related to the Anderson localization [12,13] of an unknown physical origin and questioned interpretation [14].Of paramount importance are therefore the low-energy impurity states known as zero-energy modes (ZEMs) [15,16], whose impact on the Dirac-point transport physics needs to be clarified. ZEMs are predicted or observed for a variety of disorder classes, as topological defects (mainly vacancies) [16,17], adatoms covalently bonded to carbon atoms [18,19], and extended defects as grain boundaries [20,21]. As recently confirmed by scanning tunneling microscopy experiments on graphene monovacancies [22], ZEMs manifest as wave functions that decay as the inverse of the distance from the vacancy, exhibiting a puzzling quasilocalized character, whose consequences on quantum transport remain, to date, highly controversial. First, ZEMs have been predicted to produce a supermetallic regime by enhancing the Dirac-point conductivity above its minimum ballistic value σ min = 4e 2 /πh [23,24], an unprecedented conducting state, which could be, in principle, explo...

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Impact of Vacancies on Diffusive and Pseudodiffusive Electronic Transport in Graphene

Cited by 33 publications

References 34 publications

Thermal and electronic transport characteristics of highly stretchable graphene kirigami

Thermal and electronic transport characteristics of highly stretchable graphene kirigami

Role of H Distribution on Coherent Quantum Transport of Electrons in Hydrogenated Graphene

Broken Symmetries, Zero-Energy Modes, and Quantum Transport in Disordered Graphene: From Supermetallic to Insulating Regimes

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