Tunable Band Gap in Hydrogenated Bilayer Graphene

Samarakoon, Duminda K.; Wang, Xiaoqian

doi:10.1021/nn1007868

Cited by 146 publications

(153 citation statements)

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“…When interlayer C-C bonds are created between adjacent graphene planes within AB-and AA-aligned pairs of atoms, two-dimensional (2D) nanostructures are formed resembling the atomic structures of bulk cubic and hexagonal diamond, respectively. [23][24][25][26][27]29 In TBG, where the two graphene layers are rotated with respect to each other by twist angles θ between 0° and 60°, the honeycomb lattices of each layer generate a superlattice of domains that are characterized by a specific type of local alignment; these superlattices have the same symmetry with but a larger periodicity than the original honeycomb lattice and are called Moiré patterns. [43][44][45][46] For twist angles over the range from 0° to ~16° (or, equivalently, from ~44° to 60°), these local domains consist of AAand AB-stacked atoms.…”

Section: Atomic Structurementioning

confidence: 99%

“…[20][21][22] In multilayer graphene, another way of introducing sp 3 bonding and altering the electronic band structure is the formation of interlayer bonds, namely, covalent C-C bonds between atoms of adjacent graphene layers. 16 Several theoretical studies have demonstrated that hydrogenation and formation of such interlayer bonds usually opens a band gap in the electronic band structure; [23][24][25][26][27] again, however, depending on the spatial arrangement of these interlayer bonds, certain features of the electronic band structure of the pristine, non-bonded configuration are preserved. 16 In a recent study, 16 we showed that creation of interlayer C-C bonds in TBG with the individual graphene planes rotated with respect to each other by angles around 30° leads to the formation of superlattices of caged structures (fullerenes) that have the same periodicity with that of the Moiré pattern characteristic of the TBG; depending on the size of these local fullerene structures, the Dirac cones are either preserved or lost opening a narrow gap in the band structure.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies reported structures formed by interlayer bonding in AA-and ABstacked graphene bilayers, [23][24][25][26][27] as well as in MWCNTs of mixed chirality. 29 In those studies, hydrogen atoms at a surface coverage of 50% were used to passivate dangling bonds at the outer surfaces, being distributed on the surface in a checkerboard pattern; it was shown that the presence of these chemisorbed H atoms stabilized the interlayerbonded structures.…”

mentioning

confidence: 99%

“…29 In those studies, hydrogen atoms at a surface coverage of 50% were used to passivate dangling bonds at the outer surfaces, being distributed on the surface in a checkerboard pattern; it was shown that the presence of these chemisorbed H atoms stabilized the interlayerbonded structures. The resulting configurations are characterized by a local crystalline structure that resembles that of diamond; some authors have called them "diamane" or "diamond-like C 2 H nanolayer", 24,27 while others have used the terms "hydrogenated bilayer graphene", 25 "hydrogenated few layer graphene", 26 or bilayer graphane. 23 In the study of Ref.…”

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confidence: 99%

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Opening and tuning of band gap by the formation of diamond superlattices in twisted bilayer graphene

Muniz

Maroudas

2012

Phys. Rev. B

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We report results of first-principles density functional theory calculations, which introduce a new class of carbon nanostructures formed due to creation of covalent interlayer C-C bonds in twisted bilayer graphene (TBG). This interlayer bonding becomes possible by hydrogenation of the graphene layers according to certain hydrogenation patterns. The resulting relaxed configurations consist of two-dimensional (2D) superlattices of diamond-like nanocrystals embedded within the graphene layers, with the same periodicity as that of the Moiré pattern corresponding to the rotational layer stacking in TBG. The 2D diamond nanodomains resemble the cubic or the hexagonal diamond phase. The detailed structure of these superlattice configurations is determined by parameters that include the twist angle, ranging from 0 to ~15 o , and the number of interlayer C-C bonds formed per unit cell of the superlattice. We demonstrate that formation of such interlayer-bonded finite domains causes the opening of a band gap in the electronic band structure of TBG, which depends on the density and spatial 2 distribution of interlayer C-C bonds. We have predicted band gaps as wide as 1.2 eV and found that the band gap increases monotonically with increasing size of the embedded diamond nanodomain in the unit cell of the superlattice. Such nanostructure formation constitutes a promising approach for opening a precisely tunable band gap in bilayer graphene.

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Section: Atomic Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Opening and tuning of band gap by the formation of diamond superlattices in twisted bilayer graphene

Muniz

Maroudas

2012

Phys. Rev. B

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“…32,33 We therefore next calculate the effects of an external electric field on electronic structures of bi-layer graphene/β-Si 3 N 4 . The electric field is applied in the direction perpendicular to the graphene with the positive direction pointing from graphene to Si 3 N 4 .…”

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Graphene on β-Si3N4: An ideal system for graphene-based electronics

et al. 2011

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One of the most severe limits in future design of graphene-based electronic devices is that when supported on a substrate, the electron mobility of graphene is often reduced by an order of magnitude or more. In this paper, via theoretical calculations, we show that the non-polar β-Si3N4 (0001) surface may be an excellent support for both single-layer or bi-layer graphene to overcome this limit. Since the high-κ dielectric material is an indispensable component in integrated circuits, the silicon nitride supported graphene as discussed in this paper may provide an ideal platform for future graphene-based electronics.

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Synthesis of Layer‐Tunable Graphene: A Combined Kinetic Implantation and Thermal Ejection Approach

Wang

Zhang

Liu

et al. 2015

Adv Funct Materials

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wileyonlinelibrary.comstructure and extraordinary physical properties. [1][2][3][4] To realize the potential of graphene in nanoelectronic devices, a uniform graphene layer with a well-controlled layer number should be synthesized fi rst because most of the physicochemical properties of graphene are sensitive to its thickness. For example, monolayer graphene has a zero band gap, whereas Bernal-stacked (AB-stacked) bilayer graphene is of signifi cant interest for graphene-based fi eld-effect transistors (FETs) and tunable laser diodes, [5][6][7] because of the feasibility to continuously tune up its band gap to 250 mV by applying a perpendicular electric fi eld. However, precise control of the thickness of graphene remains a major challenge. For the carbon-soluble materials (e.g., Ni, [ 8 ] Co, [ 9 ] Ru, [ 10 ] Pd, [ 11 ] and Mo [ 12 ] ), the chemical vapor deposition (CVD) synthesis of graphene proceeds via surface segregation followed by precipitation. Since the precipitation process is nonequilibrium, it is extremely challenging to tune the layer number of graphene using carbon-soluble metals in theory, though several approaches have attempted by reducing metal fi lm thickness Layer-tunable graphene has attracted broad interest for its potentials in nanoelectronics applications. However, synthesis of layer-tunable graphene by using traditional chemical vapor deposition method still remains a great challenge due to the complex experimental parameters and the carbon precipitation process. Herein, by performing ion implantation into a Ni/Cu bilayer substrate, the number of graphene layers, especially single or double layer, can be controlled precisely by adjusting the carbon ion implant fl uence. The growth mechanism of the layer-tunable graphene is revealed by monitoring the growth process, it is observed that the entire implanted carbon atoms can be expelled toward the substrate surface and thus graphene with designed layer number can be obtained. Such a growth mechanism is further confi rmed by theoretical calculations. The proposed approach for the synthesis of layer-tunable graphene offers more fl exibility in the experimental conditions. Being a core technology in microelectronics processing, ion implantation can be readily implemented in production lines and is expected to expedite the application of graphene to nanoelectronics.

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Tunable Band Gap in Hydrogenated Bilayer Graphene

Cited by 146 publications

References 45 publications

Opening and tuning of band gap by the formation of diamond superlattices in twisted bilayer graphene

Opening and tuning of band gap by the formation of diamond superlattices in twisted bilayer graphene

Graphene on β-Si3N4: An ideal system for graphene-based electronics

Synthesis of Layer‐Tunable Graphene: A Combined Kinetic Implantation and Thermal Ejection Approach

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