Sticky problem snares wonder material

Brumfiel, Geoff

doi:10.1038/495152a

Cited by 40 publications

(37 citation statements)

References 7 publications

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“…1a), silicene is relatively sticky and unstable due to its puckered or crinkled structure (Fig. 1b) 6 . To produce silicene, the hot vapor of silicon atoms is condensed onto crystalline blocks of silver 7–16 or other materials 17–19 .…”

Section: Introductionmentioning

confidence: 99%

Flat building blocks for flat silicene

Takahashi

2017

Sci Rep

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Silicene is the silicon equivalent of graphene, which is composed of a honeycomb carbon structure with one atom thickness and has attractive characteristics of a perfect two-dimensional π-conjugated sheet. However, unlike flat and highly stable graphene, silicene is relatively sticky and thus unstable due to its puckered or crinkled structure. Flatness is important for stability, and to obtain perfect π-conjugation, electron-donating atoms and molecules should not interact with the π electrons. The structural differences between silicene and graphene result from the differences in their building blocks, flat benzene and chair-form hexasilabenzene. It is crucial to design flat building blocks for silicene with no interactions between the electron donor and π-orbitals. Here, we report the successful design of such building blocks with the aid of density functional theory calculations. Our fundamental concept is to attach substituents that have sp-hybrid orbitals and act as electron donors in a manner that it does not interact with the π orbitals. The honeycomb silicon molecule with BeH at the edge designed according to our concept, clearly shows the same structural, charge distribution and molecular orbital characteristics as the corresponding carbon-based molecule.

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Section: Introductionmentioning

confidence: 99%

Flat building blocks for flat silicene

Takahashi

2017

Sci Rep

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“…On the other hand, the experimental fabrication of silicene‐based devices remains substantially challenging because silicene itself is unstable in air . A silicene field‐effect transistor (FET) was recently fabricated by Tao et al through a growth‐transfer‐fabrication approach .…”

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confidence: 99%

Stable Silicene in Graphene/Silicene Van der Waals Heterostructures

Zhang

Wang

et al. 2018

Advanced Materials

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anode material [14,15] and nanocapacitor, [16] and the silicene-arsenene vertical heterostructure is predicted to be useful in nanoelectronic and optoelectronic devices. [17] On the other hand, the experimental fabrication of silicene-based devices remains substantially challenging because silicene itself is unstable in air. [18,19] A silicene field-effect transistor (FET) was recently fabricated by Tao et al. through a growthtransfer-fabrication approach. [13,20] A roomtemperature mobility of ≈100 cm 2 V −1 s −1 was measured in their device, which, however, degraded in air after ≈2 min. Du et al. proposed another method to increase the chemical resistance of silicene to oxygen. [21] They fabricated bilayer silicene on Ag(111) and intercalated oxygen atoms which oxidized the bottom layer. While the stability of the top silicene layer improved, Raman data indicate extensive degradation of the sample in air after 120 h. Molle et al. successfully stabilized silicene by capping it with Al or Al 2 O 3 film. [22] Silicene encapsulated between the capping layer and the metal substrate was shown to be stable in ambient conditions, but the existence of a few-nm-thick capping layer does not allow the fabrication of silicene-based heterostructures.Moreover, silicene-based van der Waals heterostructures, which have been studied theoretically, [14][15][16][17] have not been experimentally demonstrated yet. Kiraly et al. deposited carbon and silicon on Ag(111) surface and found both lateral and vertical graphene-silicon heterostructures, but the Si atoms are sp 3 -bonded as in bulk crystalline Si, [23] not silicene. De Crescenzi et al. demonstrated the growth of silicene nanosheets on a graphite surface in ultrahigh vacuum. [24] While the interaction between the silicene layer and the graphite was found to be van der Waals type, the structure would be unstable in air.In this paper, we report the experimental fabrication of graphene/silicene van der Waals heterostructures. The graphene layer is grown first on a Ru(0001) substrate and silicene is constructed under it by Si intercalation. By controlling the amount of silicon, different types of silicene nanostructures are fabricated under graphene and imaged by scanning tunneling microscopy (STM). At low dosage, a periodic array of silicene-like patches under the atop regions of the graphene moiré pattern is a new type of intrinsically patterned [25] 2D material. At higher dosages, the intercalated Si forms a silicene monolayer. Covalent bonding between neighboring Si atoms in this silicene layer and weak interactions between graphene Silicene-based van der Waals heterostructures are theoretically predicted to have interesting physical properties, but their experimental fabrication has remained a challenge because of the easy oxidation of silicene in air. Here, the fabrication of graphene/silicene van der Waals heterostructures by silicon intercalation is reported. Density functional theory calculations show weak interactions between graphene and silicene layers, confirming the f...

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“…Silicene, a monolayer of silicon atoms arranged in a honeycomb lattice, received an enormous interest for being a candidate two-dimensional material that could bring the exotic electronic structure of graphene [1] to the well-developed silicon-based technology [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Single-layer free-standing silicene has been predicted to be stable [2] and was experimentally synthesized on Ag (111) substrates [4,[7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Atomic structure of the3×3phase of silicene on Ag(111)

et al. 2014

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The growth of the √ 3 × √ 3 reconstructed silicene on Ag substrate has been frequently observed in experiments while its atomic structure and formation mechanism is poorly understood. Here, by first-principles calculations, we show that √ 3 × √ 3 reconstructed silicene is constituted by dumbbell units of Si atoms arranged in a honeycomb pattern. Our model shows excellent agreement with the experimentally reported lattice constant and STM image. We propose a new mechanism for explaining the spontaneous and consequential formation of √ 3 × √ 3 structures from 3 × 3 structures on Ag substrate. We show that the √ 3 × √ 3 reconstruction is mainly determined by the interaction between Si atoms and have weak influence from Ag substrate. The proposed mechanism opens the path to understanding of multilayer silicon.

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Sticky problem snares wonder material

Cited by 40 publications

References 7 publications

Flat building blocks for flat silicene

Flat building blocks for flat silicene

Stable Silicene in Graphene/Silicene Van der Waals Heterostructures

Atomic structure of the3×3phase of silicene on Ag(111)

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