Evidence for a New Two‐Dimensional C<sub>4</sub>H‐Type Polymer Based on Hydrogenated Graphene

Haberer, Danny; Giusca, Cristina E.; Wang, Ying; Sachdev, Hermann; Fedorov, Alexander; Farjam, Mani; Jafari, S. A.; Vyalikh, D. V.; Usachov, Dmitry Yu.; Liu, Xianjie; Treske, Uwe; Grobosch, M.; Vilkov, O. Yu.; Adamchuk, V. K.; Irle, Stephan; Silva, S. Ravi P.; Knupfer, M.; Büchner, B.; Grüneis, A.

doi:10.1002/adma.201102019

Cited by 99 publications

(159 citation statements)

References 47 publications

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“…Judging from the size of a band gap and the temperature-dependent resistivity of our H-Gr showing an η of 25%, we have reached the conclusion that our saturated H-Gr can have a form of para-type C 4 H (refs 31, 32, 33), a single-sided hydrogenated graphene. As a matter of fact, hydrogenation in the H-Gr happens most probably on the top surface of graphene transferred onto a SiO 2 /Si substrate, because our hydrogen atoms do not have strong enough energy to penetrate graphene due to the mild and non-destructive nature of indirect hydrogen plasma.…”

Section: Resultsmentioning

confidence: 68%

Hydrogenated monolayer graphene with reversible and tunable wide band gap and its field-effect transistor

et al. 2016

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Graphene is currently at the forefront of cutting-edge science and technology due to exceptional electronic, optical, mechanical, and thermal properties. However, the absence of a sizeable band gap in graphene has been a major obstacle for application. To open and control a band gap in functionalized graphene, several gapping strategies have been developed. In particular, hydrogen plasma treatment has triggered a great scientific interest, because it has been known to be an efficient way to modify the surface of single-layered graphene and to apply for standard wafer-scale fabrication. Here we show a monolayer chemical-vapour-deposited graphene hydrogenated by indirect hydrogen plasma without structural defect and we demonstrate that a band gap can be tuned as wide as 3.9 eV by varying hydrogen coverage. We also show a hydrogenated graphene field-effect transistor, showing that on/off ratio changes over three orders of magnitude at room temperature.

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Section: Resultsmentioning

confidence: 68%

Hydrogenated monolayer graphene with reversible and tunable wide band gap and its field-effect transistor

et al. 2016

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“…Though experimental studies have shown adsorption-induced metal-insulator transitions, 7,8 reversible opening of a band-gap 9,10 and even ferromagnetic hysteresis, 11 the necessary precise control on the hydrogenation process has yet to be achieved. Hydrogenation of graphite has been studied in a number of experimental works, 3,[12][13][14][15][16][17][18][19][20][21][22][23][24] with a variety of surface-science techniques including thermal desorption, high-resolution electron-energy-loss spectroscopy, scanning tunneling microscopy, low-energy electron diffraction, angle a) Electronic mail: matteo.bonfanti@unimi.it b) Electronic mail: rocco.martinazzo@unimi.it resolved photo-emission spectroscopy, and X-ray photoemission spectroscopy. It has now been well established that sticking is an activated process, with a barrier related to the surface reconstruction accompanying the sp 2 → sp 3 re-hybridization of the carbon atom involved in the bond formation process.…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamics of hydrogen atoms on graphene. II. Sticking

Bonfanti

Jackson

Hughes

et al. 2015

The Journal of Chemical Physics

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Study of the sticking of a hydrogen atom on a graphite surface using a mixed classical-quantum dynamics method J. Chem. Phys. 133, 044508 (2010); 10.1063/1.3463001Reuse of AIP Publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. (2015)], we present the results of converged quantum scattering calculations on the activated sticking dynamics. The focus of this study is the collinear scattering on a surface at zero temperature, which is treated with high-dimensional wavepacket propagations with the multi-configuration time-dependent Hartree method. At low collision energies, barrier-crossing dominates the sticking and any projectile that overcomes the barrier gets trapped in the chemisorption well. However, at high collision energies, energy transfer to the surface is a limiting factor, and fast H atoms hardly dissipate their excess energy and stick on the surface. As a consequence, the sticking coefficient is maximum (∼0.65) at an energy which is about one and half larger than the barrier height. Comparison of the results with classical and quasi-classical calculations shows that quantum fluctuations of the lattice play a primary role in the dynamics. A simple impulsive model describing the collision of a classical projectile with a quantum surface is developed which reproduces the quantum results remarkably well for all but the lowest energies, thereby capturing the essential physics of the activated sticking dynamics investigated. C 2015 AIP Publishing LLC.[http://dx

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“…Experimentally, semihydrogenated layers might be accessible when one side of the Bi film is protected by a substrate and the other one is exposed to hydrogen. For graphene, half-hydrogenated layers have been successfully fabricated [50].…”

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confidence: 99%

Functionalized bismuth films: Giant gap quantum spin Hall and valley-polarized quantum anomalous Hall states

et al. 2015

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The search for new large band gap quantum spin Hall (QSH) and quantum anomalous Hall (QAH) insulators is critical for their realistic applications at room temperature. Here we predict, based on first principles calculations, that the band gap of QSH and QAH states can be as large as 1.01 eV and 0.35 eV in an H-decorated Bi(111) film. The origin of this giant band gap lies both in the large spin-orbit interaction of Bi and the Hmediated exceptional electronic and structural properties. Moreover, we find that the QAH state also possesses the properties of quantum valley Hall state, thus intrinsically realising the so-called valley-polarized QAH effect. We further investigate the realization of large gap QSH and QAH states in an H-decorated Bi(110) film and X-decorated (X=F, Cl, Br, and I) Bi(111) films. 71.70.Ej, Since their discovery [1,2], there is growing interest in topological insulators (TIs), which host conducting surface states inside the bulk insulating gap. The gapless surface states are topologically protected by time reversal symmetry (TRS) and robust to nonmagnetic perturbations [3][4][5]. The first theoretically predicted [6] and experimentally observed [7] TI is a HgTe/CdTe quantum well structure that is a two-dimensional (2D) TI, also known as quantum spin Hall (QSH) insulator. In a QSH insulator, pairs of dissipationless edge channels with opposite spins exist, leading to extraordinary properties and possible applications in low dissipation electronic devices. On the other hand the realization of the Quantum Anomalous Hall (QAH) effect, which was first suggested to occur in a honeycomb lattice model [8], has been achieved recently in Cr-doped topological insulators (Bi,Sb) 2 Te 3 [9] via suppressing one of the spin channels [10,11], but requires extremely low temperatures (30 mK). For obtaining the room temperature QSH-and QAHbased electronic devices, searching for novel materials with large band gaps as well as stable atomic and magnetic structures has been a fairly important topic in the field. In spite of extensive efforts so far [12][13][14][15][16][17][18][19][20][21][22][23][24], most of known systems with desired topological properties have a small band gap, which greatly obstructs their potential room temperature applications.Valley polarization, as a new degree of freedom in honeycomb lattices in addition to the intrinsic charge and spin, has received considerable attention in recent years [25,26]. The valley Hall conductivity can be non-zero when the inversion symmetry is broken, realizing the quantum-valley Hall (QVH) effect characterized by so-called valley Chern number [25]. Quite recently, a new quantum state, valley-polarised QAH state that exhibits the electronic properties of both QVH state and QAH state has been predicted in silicene through tuning the extrinsic spin-orbit coupling (SOC) with broken TRS [27]. It provides a new way to design the dissipationless valleytronics. However, the presence of both, inversion symmetry and TRS, as well as the small SOC in pristine silicene ...

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Evidence for a New Two‐Dimensional C₄H‐Type Polymer Based on Hydrogenated Graphene

Cited by 99 publications

References 47 publications

Hydrogenated monolayer graphene with reversible and tunable wide band gap and its field-effect transistor

Hydrogenated monolayer graphene with reversible and tunable wide band gap and its field-effect transistor

Quantum dynamics of hydrogen atoms on graphene. II. Sticking

Functionalized bismuth films: Giant gap quantum spin Hall and valley-polarized quantum anomalous Hall states

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Evidence for a New Two‐Dimensional C4H‐Type Polymer Based on Hydrogenated Graphene

Cited by 99 publications

References 47 publications

Hydrogenated monolayer graphene with reversible and tunable wide band gap and its field-effect transistor

Hydrogenated monolayer graphene with reversible and tunable wide band gap and its field-effect transistor

Quantum dynamics of hydrogen atoms on graphene. II. Sticking

Functionalized bismuth films: Giant gap quantum spin Hall and valley-polarized quantum anomalous Hall states

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Evidence for a New Two‐Dimensional C₄H‐Type Polymer Based on Hydrogenated Graphene